Systems and methods for patient fall detection

ABSTRACT

A patient monitoring system to help manage a patient that is at risk of falling is disclosed. The system includes a patient-worn wireless sensor that senses the patient&#39;s motion and wirelessly transmits information indicative of the sensed motion to a patient monitor. The patient monitor receives, stores, and processes the transmitted information to determine whether the patient has fallen or is about to fall. Upon such detection, the system can notify the patient&#39;s caretakers that the patient has fallen or is about to fall and therefore, is in need of immediate attention.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

The present application claims priority benefit under 35 U.S.C. § 119(e)to U.S. Provisional Application No. 62/212,467, filed Aug. 31, 2015,U.S. Provisional Application No. 62/212,472, filed Aug. 31, 2015, U.S.Provisional Application No. 62/212,484, filed Aug. 31, 2015, and U.S.Provisional Application No. 62/212,480, filed Aug. 31, 2015, which arehereby incorporated by reference herein in entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to the field of patient monitoring. Morespecifically, the disclosure describes among other things a wearablesensor that measures a patient's position, orientation, and movement andwirelessly communicates the measured information to a patient monitoringsystem.

BACKGROUND

In clinical settings, such as hospitals, nursing homes, convalescenthomes, skilled nursing facilities, post-surgical recovery centers, andthe like, patients are frequently confined to bed for extended periodsof time. Sometimes the patients are unconscious or sedated to such anextent that they have limited ability to change or control theirposition in the bed. These patients can be at risk of forming pressureulcers, which pose a serious risk to the patient's health andwell-being. Pressure ulcers, which may also be referred to as “bedsores,” “pressure sores,” and “decubitus ulcers,” comprise injury to apatient's skin, and often the underlying tissue, which results fromprolonged pressure forces applied to a site on the patient's body.Frequently, pressure ulcers develop on skin that covers bony areas ofthe body which have less muscle and/or fat tissue below the surface todistribute pressure applied thereto resulting from prolonged contactwith the surface of a bed or chair. Examples of such body locationsinclude the back or side of the head, shoulders, shoulder blades,elbows, spine, hips, lower back, tailbone, heels, ankles, and skinbehind the knees.

Pressure ulcers are caused by application of pressure at an anatomicalsite that occludes blood flow to the skin and other tissue near thelocation. Sustained pressure between a structural surface (such as abed) and a particular point on the patient's body can restrict bloodflow when the applied pressure is greater than the blood pressureflowing through the capillaries that deliver oxygen and other nutrientsto the skin and other tissue. Deprived of oxygen and nutrients, the skincells can become damaged, leading to tissue necrosis in as few as 2 to 6hours. Despite commonly occurring in elderly and mobility-impairedpopulations, hospital-acquired pressure ulcers are considered to bepreventable and have been termed “never events.” Insurers have imposedrestrictions on the amount they will reimburse a hospital for pressureulcer treatment, and state and federal legislation now requireshospitals to report the occurrence of pressure ulcers in theirfacilities.

Risk factors for pressure ulcers can be categorized as modifiable andnon-modifiable. Modifiable risk factors include actions that healthcareproviders can take, while non-modifiable risk factors include aspects ofpatient health and behavior. It is valuable to document suchnon-modifiable risk factors so that caregivers can identify and attendto patients at risk of developing pressure ulcers. It is recommendedthat caregivers develop a documented risk assessment policy to predictthe risk of a patient developing a pressure ulcer. Such an assessmentcan encompass all aspects of a patient's health and environment, and mayemploy commonly used measures in the field, such as the Braden andNorton scales. The risk assessment tool may be used to directpreventative strategies not only when a patient is at rest in his or herbed, but also when undergoing surgery.

Additional factors that can contribute to the formation of pressureulcers include friction and shear forces. Friction can occur when skinis dragged across a surface which can happen when patients are moved,especially when the skin is moist. Such frictional forces can damage theskin and make it more vulnerable to injury, including formation of apressure ulcer. A shear is when two forces move in opposite directions.For example, when the head portion of a bed is elevated at an incline,the patient's spine, tailbone, and hip regions tend to slide downwarddue to gravity. As the bony portion of the patient's body movesdownward, the skin covering the area can stay in its current position,thereby pulling in the opposite direction of the skeletal structure.Such shear motion can injure the skin and blood vessels at the site,causing the skin and other local tissue to be vulnerable to formation ofa pressure ulcer.

An established practice for patients at risk of forming pressure ulcersis to follow a turning protocol by which the patient is periodicallyrepositioned, or “turned” to redistribute pressure forces placed onvarious points of the patient's body. Individuals at risk for a pressureulcer are be repositioned regularly. It is commonly suggested thatpatients be repositioned every 2 hours at specific inclination angles,and that the method of doing so minimizes the amount of friction andshear on the patient's skin. A repositioning log can be maintained andinclude key information, such as the time, body orientation, andoutcome.

Pressure ulcer prevention programs have been effective and can reducelong-term costs associated with treatment. A 2002 study employed acomprehensive prevention program in two long-term care facilities,costing $519.73 per resident per month. Results of the program revealedpressure ulcer prevalence to be reduced by 87% and 76% in the twofacilities. A later study found that prevention strategies were able toreduce pressure ulcer prevalence from 29.6% to 0% in a medical intensivecare unit, and from 9.2% to 6.6% across all units of the hospital. Theseinterventions employed strategies such as manual patient repositioningand logging, tissue visualization and palpation, pressure-reducingmattresses, and use of risk assessment tools.

Turning protocols, however, do not take into consideration positionchanges made by the patient between established turn intervals, whichare neither observed nor recorded. Thus it is possible that in somecircumstances, the act of following a turn protocol can have anunintended negative clinical effect.

SUMMARY

This disclosure describes, among other things, embodiments of systems,devices, and methods for monitoring the position and orientation of apatient at risk of forming one or more pressure ulcers.

One aspect of the present disclosure comprises a patient turn andmovement monitoring system configured to help manage a patient that isat risk of forming one or more pressure ulcers. Some embodiments of thepatient turn and monitoring system include a patient-worn, wirelesssensor having one or more sensors configured to obtain informationdescribing the patient's orientation and to wirelessly transmitinformation indicative of the sensed orientation information. The systemalso includes a patient monitor configured to receive, store, andprocess the information transmitted by the wireless sensor and todisplay and transmit information (or data) indicative of the patient'sorientation to help caregivers manage the patient's risk of formation ofone or more pressure ulcers. The patient turn and movement monitoringsystem can identify the present orientation of the patient and determinehow long the patient has been in the present orientation. If the patientremains in an orientation beyond a predefined, clinician-prescribedpatient orientation duration, the system can notify the patient and/orcaretakers that the patient is due to be repositioned. In certainembodiments, a patient orientation duration timer is used to monitorsuch orientation times. In certain embodiments of the disclosed patientturn and movement monitoring system, a signal repeater, located withinreception range of the wireless sensor, is used to receive and forwardthe information indicative of the sensed orientation information fromthe wireless sensor to a network-based processing node.

Another aspect of the present disclosure includes a wireless sensorincluding one or more sensors configured to obtain position,orientation, and motion information from the patient. The one or moresensors can include an accelerometer, a gyroscope, and a magnetometer,which are configured to determine the patient's position and orientationin three-dimensional space. The wireless sensor is configured towirelessly transmit the sensor data, and/or information representativeof the sensor data, to a patient monitor. The patient monitor can beconfigured to process the received information, to display informationindicative of, or derived from the received data, and to transmitinformation—including displays, alarms, alerts, and notifications—to amulti-patient monitoring system which may be located, for example, at anurse's station.

Another aspect of the present disclosure is directed to a system andmethod for associating the wireless sensor with a patient monitor. Insome embodiments, the wireless sensor includes an activation tab which,when removed, activates the wireless sensor. Upon activation, a wirelesstransceiver in the wireless sensor emits a low-power pairing signalhaving a pairing signal transmission range of up to approximately threeinches. In some embodiments, the wireless sensor has a switch or buttonwhich, when depressed, places the wireless sensor in a pairing mode ofoperation, causing the wireless sensor to emit the low-power pairingsignal. When the patient monitor is within range of the wireless sensor(e.g., within the about three-inch range), the wireless sensor and thepatient monitor associate, thereby configuring the wireless sensor andpatient monitor to communicate with each other. Once the pairing betweenthe wireless sensor and the patient monitor is completed, the wirelesssensor changes into a patient parameter sensing mode of operation inwhich the wireless sensor transmits a patient parameter sensing signal.The patient parameter sensing signal has a patient signal transmissionrange that is substantially greater than the pairing signal transmissionrange. The wireless sensor is then in condition to be placed on thepatient.

In some aspects of the present disclosure the patient's position andorientation are monitored and recorded. Once the wireless sensor isaffixed to the patient's body, such as, for example, the patient'storso, sensor data corresponding to the patient's motion (e.g.,acceleration and angular velocity) are obtained, pre-processed, andtransmitted to the patient monitor. The patient monitor stores andfurther processes the received data to determine the patient'sorientation. Illustratively, the patient monitor can determine whetherthe patient is standing, sitting, or lying down in the prone, supine,left side, or right side positions.

In some embodiments, the patient monitor determines the preciseorientation of the patient's body. For example, the patient monitor candetermine the degree to which the patient's body is inclined, verticallyand/or horizontally, thereby generating an accurate description of thepatient's position relative to the support structure (such as a bed)upon which the patient lies.

In another aspect of the present disclosure the patient monitor storesthe determined position and orientation information and keeps track ofhow long the patient remains in each determined position, therebycreating a continuous record of the patient's positional history. Thepatient monitor analyzes and processes the stored data to provideclinically-relevant, actionable information to the patient's careproviders. Illustratively, the patient monitor counts the number ofin-bed turns performed by the patient and monitors and displays theamount of time that has elapsed since the patient last turned. When theelapsed time exceeds a clinician-defined duration (e.g., two hours), thepatient monitor displays an indication that the maximum time betweenpatient turns has been exceeded. The patient monitor can also transmit anotification to one or more clinicians responsible for caring for thepatient via, for example, a multi-patient monitoring system, a cliniciannotification device, or the like. The patient monitor can also determineand display statistical information, such as the average, minimum, andmaximum amount of time between turns for a given clinician-defined timeperiod, such as for example, twenty-four hours. The patient monitor canalso determine and display the number of turns in the same position andorientation over a clinician-defined period of time. Similarly, thepatient monitor can display the total amount of time the patientremained in each specific position within a clinician-defined period.Moreover, the patient monitor can determine the frequency and durationof periods during which the patient remained in clinically-definedacceptable positions.

In yet another aspect of the present disclosure the patient monitordetermines the mobility status of the patient, e.g., whether the patientis ambulatory, standing, sitting, reclining, or falling. In certainaspects, the wireless monitoring system can include an alert system toalert the caregiver that the patient is falling, getting out of bed, orotherwise moving in a prohibited manner or in a manner that requirescaregiver attention. The alert can be an audible and/or visual alarm onthe monitoring system, or the alert can be transmitted to a caregiver(e.g., nurses' station, clinician device, pager, cell phone, computer,or otherwise). Illustratively, the patient monitor can display thepatient's mobility status and transmit a notification that the patientis active and away from the bed. In some circumstances, the patientmonitor can determine whether the patient contravenes a clinician'sorder, such as, for example, instructions to remain in bed, or to walkto the bathroom only with the assistance of an attendant. In suchcircumstances, a notification, alert, or alarm can be transmitted to theappropriate caregivers.

In certain aspects, the information received by the wireless sensor canbe used to create a time-sequenced representation of the patient'smovement. This representation can be displayed on the patient monitor ortransmitted to a nurses' station or other processing nodes to enable thecaregiver to monitor the patient. The time-sequenced representation canbe viewed in real time and/or be recorded for playback. For example, ifan alarm alerts the caregiver that the patient has fallen out of bed,the caregiver can access and review the historical sequence of thepatient's movements prior to and during that period of time.

Another aspect of the present disclosure is directed to predicting apatient's risk of falling based on the patient's gait and otherinformation (such as, for example, the patient's current medicationregimen). When the patient monitor determines that the patient's risk offalling is above a predetermined threshold, the patient monitor canissue an alarm or alert to notify care providers of the identified riskin an effort to anticipate and therefore prevent a patient fall.Additionally, the patient monitor can determine when a patient hasfallen and issue the appropriate alarms and alerts to summon careprovider assistance.

In an aspect of the present disclosure the patient monitor accesses thepatient's health records and clinician input via a network.Illustratively, the patients' positional history data, analyzed in viewof the patient's health records, may reveal or suggest a turningprotocol (or other treatment protocol) that will likely yield favorableclinical outcomes for the particular patient. Accordingly, the patientmonitor analyzes the accessed information in conjunction with thereceived information from the wireless sensor to determine a recommendedpatient turn protocol (or other treatment protocol) for the patient.

In still another aspect of the present disclosure, the patient monitorassesses caregiver and facility compliance with the clinician-definedpatient turn protocol established for the patient. For example, thepatient monitor can identify the number of times that the patientremains in a position for a period greater than the prescribed duration,indicating a patient turn protocol violation, as well as the length ofeach such overexposure. The patient monitor can also track theclinician's response time upon issuance of a notification, alert, oralarm.

According to another aspect of the present disclosure, care providerworkflow productivity, efficiency, and effectiveness can be determined,based on aggregated positional history data corresponding to multiplepatients wherein each patient is equipped with the disclosed wirelesssensor. Additionally, care for patients in a particular location, suchas a hospital ward or nursing home floor where the ratio of patients tostaff is relatively high, can be prioritized based on the determinedrisk of formation of pressure ulcers. Thus, patients determined to havethe highest risk are designated to receive attention first.

In yet another aspect of the present disclosure, the wireless sensorincludes sensors to obtain additional physiological measurements fromthe patient. For example, the wireless sensor can include a temperaturesensor configured to measure the patient's body core body temperature byinsulating the patient's skin surface around the temperature sensor. Asa result of the insulation surrounding the temperature sensor, thenatural temperature difference between the patient's skin surface andbody core reach equilibrium, thereby arriving at the patient's body coretemperature (which is typically higher in temperature than the patient'sskin surface). The wireless sensor can also include an acousticrespiration sensor configured to sense vibrational motion generated bythe patient's chest. The acoustic respiration sensor is configured tomechanically transmit the sensed vibrations through rigid structures ofthe device to the accelerometer. Processing of the accelerometer signalcan provide, among other things, the patient's respiration and heartrates. An electrocardiogram (ECG) sensor, configured to sense electricalsignals from two or more electrodes in electrical contact with thepatient's chest may also be included in the wireless sensor. The ECGsignal can be processed to detect arrhythmias, such as bradycardia,tachyarrhythmia, ventricular fibrillation and the like. Additionally,the accelerometer signal (containing information indicative of themechanically-transmitted vibrations from the acoustic respirationsensor) and/or the ECG signal can be processed to identify respiratorydistress or dysfunction, including without limitation, snoring,coughing, choking, wheezing, apneic events, and airway obstruction.

In another aspect of the present disclosure, the patient monitor candetermine a score that describes the patient's wellness/sickness state,which may also be referred to as a “Halo Index.” Illustratively, thepatient monitor accesses and analyzes the patient's health records,clinician input, positional history data provided by the wirelesssensor, surface structure pressure data, and other physiologicalparameter data collected and provided by the wireless sensor (such as,by way of non-limiting example, the patient's temperature, respirationrate, heart rate, ECG signal, and the like) to assess the patient'soverall health condition.

In an aspect of the present disclosure, the patient monitor accessesinformation provided by the patient's support structure (e.g., bed,mattress, bed sheet, mattress pad, and the like) to determine the extentof pressure forces exerted on particular anatomical sites of thepatient's body. Illustratively, the patient's support structure can beconfigured with an array of pressure sensors that measure the pressureforce exerted on the support structure by the patient at specificlocations. The patient monitor can analyze the patient's posturalhistory data in conjunction with the information provided by the supportstructure to determine a likelihood of pressure ulcer formation at aspecific anatomical location based on the measured amount of pressureexerted on the anatomical location multiplied by the amount of time theanatomical location has been under such pressure. When the evaluatedrisk exceeds a predetermined threshold, the patient monitor can issue analarm and/or an alert to reposition the patient so as to avoid formationof a pressure ulcer in the specified anatomical location. Additionally,the patient monitor can suggest particular positions and/or a patientturn protocol based on the combined analysis of pressure force exertedand length of time under such pressure.

For purposes of summarizing the disclosure, certain aspects, advantages,and novel features have been described herein. Of course, it is to beunderstood that not necessarily all such aspects, advantages, orfeatures will be embodied in any particular embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments will be described hereinafter with reference to theaccompanying drawings. The drawings and the associated descriptions areprovided to illustrate embodiments of the present disclosure and do notlimit the scope of the claims. In the drawings, similar elements havesimilar reference numerals.

FIG. 1A is a perspective view of an embodiment of the disclosed patientmonitoring system including a patient-worn wireless sensor in proximityto a patent monitor.

FIG. 1B is a functional block diagram of an embodiment of the display ofthe disclosed patient monitor.

FIG. 1C is a functional block diagram of an embodiment of the disclosedpatient monitoring system.

FIG. 1D is a functional block diagram of an embodiment of the disclosedpatient monitoring system.

FIG. 1E is a functional block diagram of an embodiment of the disclosedpatient monitoring system.

FIG. 1F is a functional block diagram of an embodiment of the disclosedpatient monitoring system.

FIG. 2A is a functional block diagram of an embodiment of the disclosedwireless sensor.

FIG. 2B is a functional block diagram of an embodiment of the disclosedwireless sensor including optional sensing components.

FIG. 3A is a schematic exploded perspective view of an embodiment of thedisclosed wireless sensor.

FIG. 3B is a schematic assembled perspective view of the embodiment ofthe disclosed wireless sensor of FIG. 3A.

FIG. 3C is a schematic side view of the embodiment of the disclosedwireless sensor of FIGS. 3A and 3B.

FIG. 4A is a schematic cross-sectional view of an embodiment of thedisclosed wireless sensor which includes a temperature sensor.

FIG. 4B is a schematic bottom view of the embodiment of the disclosedwireless sensor of FIG. 4A.

FIG. 4C is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 4A-B.

FIG. 5A is a schematic cross-sectional view of an embodiment of thedisclosed wireless sensor which includes an acoustic respiration sensor.

FIG. 5B is a schematic bottom view of the embodiment of the disclosedwireless sensor of FIG. 5A.

FIG. 5C is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 5A-B.

FIG. 6A is a schematic cross-sectional view of an embodiment of thedisclosed wireless sensor which includes a temperature sensor and anacoustic respiration sensor.

FIG. 6B is a schematic bottom view of the embodiment of the disclosedwireless sensor of FIG. 6A.

FIG. 6C is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 6A-B.

FIG. 7A is a perspective view of an embodiment of the disclosed patientmonitoring system including a patient-worn wireless sensor having an ECGsensor in proximity to a patent monitor.

FIG. 7B is a schematic assembled perspective view of the embodiment ofthe disclosed wireless sensor of FIG. 7A.

FIG. 7C is a schematic side view of the embodiment of the disclosedwireless sensor of FIGS. 7A and 7B.

FIG. 7D is a cross-sectional view of an embodiment of the disclosedwireless sensor of FIGS. 7A-C.

FIG. 7E is a schematic bottom perspective view of the embodiment of thedisclosed wireless sensor of FIGS. 7A-D

FIG. 7F is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 7A-7E.

FIG. 8A is a schematic exploded perspective view of an embodiment of thedisclosed wireless sensor having a temperature sensor, an acousticrespiration sensor, and an ECG sensor.

FIG. 8B is a schematic bottom view of the disclosed wireless sensor ofFIG. 8A.

FIG. 9 is a flow diagram describing a process to associate a wirelesssensor with a patient monitor according to an embodiment of the presentdisclosure.

FIG. 10 is a flow diagram describing a process to determine whether apatient has changed orientation according to an embodiment of thepresent disclosure.

FIG. 11A is an exemplary plot of processed accelerometer data over timeused to determine a patient's orientation according to an embodiment ofthe present disclosure.

FIG. 11B is an exemplary plot of the duration of a patient's orientationaccording to an embodiment of the present disclosure.

FIG. 12 is a flow diagram describing a process to determine whether apatient has fallen according to an embodiment of the present disclosure.

FIGS. 13A-F illustrate embodiments of displays reflecting a patient'sposition according to an embodiment of the present disclosure.

FIG. 14 illustrates an example display of a patient monitorincorporating the icons illustrated in FIGS. 13A-F according to anembodiment of the present disclosure.

FIGS. 15A-H illustrate various configurations of a room displaydisplayed on a patient display monitor according to an embodiment of thepresent disclosure.

FIG. 16 illustrates an example method according to an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure will now be described withreference to the accompanying figures, wherein like numerals refer tolike elements throughout. The following description is merelyillustrative in nature and is in no way intended to limit thedisclosure, its application, or uses. It should be understood that stepswithin a method may be executed in different order without altering theprinciples of the present disclosure. Furthermore, embodiments disclosedherein can include several novel features, no single one of which issolely responsible for its desirable attributes or which is essential topracticing the systems, devices, and methods disclosed herein.

The present disclosure relates to systems, devices, methods, andcomputer-readable media to monitor and manage the position, orientation,and movement of a patient who is at risk of forming one or more pressureulcers. In one embodiment, the system comprises a patient-worn, wirelesssensor including one or more sensors configured to obtain position,orientation and movement information from the patient. The one or moresensors can include one or more accelerometers, gyroscopes, andmagnetometers (i.e., compasses). Illustratively, the sensorscontinuously or periodically (e.g., every second) obtain informationthat describes the patient's orientation in three dimensions. Thewireless sensor includes a processor that is configured to process theobtained sensor information. The wireless sensor also includes atransceiver configured to wirelessly transmit the processed sensor data,and/or information representative of the sensor data, to a patientmonitor (or other processing device) for further processing. The patientmonitor can be configured to store and further process the receivedinformation, to display information indicative of or derived from thereceived data, and to transmit information—including displays, alarms,alerts, and notifications—to other patient care systems including amulti-patient monitoring system which may be accessible from, forexample, a nurses' station.

FIG. 1A is a perspective illustration of an embodiment of the disclosedpatient monitoring system 100 in a clinical setting. The patientmonitoring system 100 includes a wireless sensor 102 worn by a patient,in proximity to a patient monitor 106 located on a table 116 at the sideof the patient's bed 118. The wireless sensor 102 may also be referredto herein as “a wireless physiological sensor 102,” “a patient-wornsensor 102,” “a movement sensor 102,” and “a wearable wireless sensor102.” The wireless sensor 102 includes one or more sensors configured tomeasure the patient's position, orientation, and motion. In someembodiments, the wireless sensor 102 includes an accelerometerconfigured to measure linear acceleration of the patient and a gyroscopeconfigured to measure angular velocity of the patient. The measuredlinear acceleration and angular velocity information can be processed todetermine the patient's orientation in three dimensions. In someembodiments, a magnetometer is included in the wireless sensor 102 tomeasure the Earth's gravitational field. Information measured by themagnetometer can be used to improve accuracy of the determinedorientation of the patient.

The wireless sensor 102 also includes a wireless transceiver 206 (shownin FIGS. 2A and 2B) which can transmit to the patient monitor 106information representative of sensor data obtained by the wirelesssensor 102 from the patient. Advantageously, the patient is notphysically coupled to the bedside patient monitor 106 and can thereforemove freely into different positions on the bed 118.

In accordance with certain embodiments of the present disclosure, thewireless sensor 102 is affixed to the skin of the patient's body underthe patient's garment as reflected in FIG. 1A by the phantom drawing ofthe wireless sensor 102. More particularly, the wireless sensor 102 canbe placed on the patient's chest over the patient's manubrium, the broadupper portion of the sternum. In this position, the wireless sensor 102is approximately centered relative to the longitudinal axis of thepatient's body and near the patient's center of mass, a position that isuseful in determining the patient's orientation when, for example, thepatient is in bed.

The wireless sensor 102 can be affixed to the patient's skin using anyform of medically-appropriate adherent material, including apressure-sensitive adhesive that is coated or applied to the bottomsurface of the wireless sensor 102. One skilled in the art willappreciate that many other materials and techniques can be used to affixthe wireless sensor 102 to the patient without departing from the scopeof the present disclosure.

Frequently in clinical settings, multiple medical sensors are attachedor adhered to a patient to concurrently monitor multiple physiologicalparameters. Some examples of medical sensors include, but are notlimited to, position, orientation, and movement sensors, temperaturesensors, respiration sensors, heart rate sensors, blood oxygen sensors(such as pulse oximetry sensors), acoustic sensors, EEG sensors, ECGsensors, blood pressure sensors, sedation state sensors, to name a few.Typically, each sensor that is attached to a patient transmits, often bycable, the obtained physiological data to a nearby monitoring deviceconfigured to receive and process the sensor data, and transform it intoclinical information to be used by the care providers to monitor andmanage the patient's condition. When a patient is concurrently monitoredby several physiological sensors, the number of cables and the number ofbedside monitoring devices used can be excessive and can limit thepatient's freedom of movement and impede care providers' access to thepatient. The cables connecting the patient to the bedside monitoringdevices can also make it more difficult to move the patient from room toroom or to switch to different bedside monitors.

Advantageously, the disclosed wireless sensor 102 can transmit data,wirelessly, to a patient data processing environment 105 in which thesensor data can be processed using one or more processing capabilities.As illustrated in FIG. 1A, the wireless sensor 102 transmits data via awireless communications link 104. The wireless communications link 104can be received by the bedside patient monitor 106, and/or by anextender/repeater 107. Both the patient monitor 106 andexpander/repeater 107 provide access, by way of high-speed and reliablecommunications interfaces, to the patient data processing environment105. For illustration purposes, both the patient monitor 106 and theextender/repeater 107 are illustrated in FIG. 1A. However, typicallyonly one such device is required to establish a wireless connectionbetween the wireless sensor 102 and the patient data processingenvironment 105. The wireless communications link 104 can use any of avariety of wireless technologies, such as Wi-Fi (802.11x), Bluetooth,ZigBee, cellular telephony, infrared, RFID, satellite transmission,proprietary protocols, combinations of the same, and the like. Thewireless sensor 102 can be configured to perform telemetry functions,such as measuring and reporting position, orientation, and movementinformation about the patient. According to one embodiment, the wirelesssensor 102 uses the Bluetooth wireless communications standard tocommunicate wirelessly with the patient monitor 106.

The extender/repeater 107 can receive sensor data from the wirelesssensor 102 by way of the wireless communications link 104 and forwardthe received sensor data, via the network 108, to one or more processingnodes within the patient data processing environment 105. For example,the extender/repeater 107 can forward the received sensor data to apatient monitor 106 that might be located beyond the range of thewireless communications link 104 of a particular wireless sensor 102.Alternatively, the extender/repeater 107 can route the sensor data toother processing nodes within the patient data processing environment105, such as, for example, a multi-patient monitoring system 110 or anurses' station system 113. A skilled artisan will appreciate thatnumerous processing nodes and systems can be used to process the datatransmitted by the wireless sensor 102.

FIG. 1A also illustrates an embodiment of the patient monitor 106, whichmay also be referred to herein as “a processing device 106,” “a portablecomputing device 106,” and “a patient monitoring device 106.” Examplesof a patient monitor 106 are disclosed in U.S. Pat. Pub. Nos.2013/0262730 and 2015/0099955, assigned to the assignee of the presentdisclosure, and which are incorporated by reference herein in theirentirety. The patient monitor 106 is a processing device, and thereforeincludes the necessary components to perform the functions of aprocessing device, including at least one processor, a memory device, astorage device, input/output devices, and communications connections,all connected via one or more communication buses. Thus, in certainembodiments, the patient monitor 106 is configured to process the sensordata provided by the wireless sensor 102. In other embodiments,processing of the sensor data can be performed by other processing nodeswithin the patient data processing environment 105. The patient monitor106 is configured to wirelessly communicate with the wireless sensor102. The patient monitor 106 includes a display 120, and a dockingstation, which is configured to mechanically and electrically mate witha portable patient monitor 122 also having a display 130. The patientmonitor 106 is housed in a movable, mountable, and portable housingformed in a generally upright, inclined shape configured to rest on ahorizontal flat surface, as shown in FIG. 1A. Of course, a personskilled in the art will appreciate that the housing can be affixed in awide variety of positions and mountings and can comprise a wide varietyof shapes and sizes.

In an embodiment, the display 120, alone or in combination with thedisplay 130 of the portable patient monitor 122, may present a widevariety of measurement and/or treatment data in numerical, graphical,waveform, or other display indicia. For example, the display 120 candisplay a variety of patient-specific configurations and/or parameters,such as the patient's weight, age, type of treatment, type of disease,type of medical condition, nutrition, hydration and/or length of stay,among others. In an embodiment, the display 120 occupies much of a frontface of the housing, although an artisan will appreciate the display 120may comprise a table or tabletop horizontal configuration, a laptop-likeconfiguration, or the like. Other embodiments may include communicatingdisplay information and data to a tablet computer, smartphone,television, or any display system recognizable to an artisan.Advantageously, the upright inclined configuration of the patientmonitor 106, as illustrated in FIG. 1A, displays information to acaregiver in an easily viewable manner.

The portable patient monitor 122 of FIG. 1A may advantageously includean oximeter, co-oximeter, respiratory monitor, depth of sedationmonitor, noninvasive blood pressure monitor, vital signs monitor or thelike, such as those commercially available from Masimo Corporation ofIrvine, Calif., and/or disclosed in U.S. Pat. Pub. Nos. 2002/0140675,2010/0274099, 2011/0213273, 2012/0226117, 2010/0030040; U.S. patentapplication Ser. Nos. 61/242,792, 61/387,457, 61/645,570, 13/554,908 andU.S. Pat. Nos. 6,157,850, 6,334,065, the contents of which areincorporated herein by reference in their entireties. The portablepatient monitor 122 may communicate with a variety of noninvasive and/orminimally invasive devices such as, by way of non-limiting example,wireless sensor 102, optical sensors with light emission and detectioncircuitry, acoustic sensors, devices that measure blood parameters froma finger prick, cuffs, ventilators, and the like. The portable patientmonitor 122 may include its own display 130 presenting its own displayindicia. The display indicia may change based on a docking state of theportable patient monitor 122. When undocked, the display 130 may includeparameter information and may alter its display orientation based oninformation provided by, for example, a gravity sensor or anaccelerometer. Although disclosed with reference to particular portablepatient monitors 122, an artisan will recognize from the disclosureherein there is a large number and wide variety of medical devices thatmay advantageously dock with the patient monitor 106.

FIG. 1B is a functional block diagram of an embodiment of the display120 of the disclosed patient monitor 106 and the display 130 of theportable patient monitor 122. Display 120 of the patient monitor 106 canbe configured to present patient physiological data 124, patient turndata 126, and/or additional, optional patient data 128. Patientphysiological data can include, by way of non-limiting example, oxygensaturation, pulse rate, respiration rate, fractional arterial oxygensaturation, total hemoglobin, plethysmograph variability index,methemoglobin, carboxyhemoglobin, perfusion index, and oxygen content.Advantageously, the display 120 is configurable to permit the user toadjust the manner by which the physiologic parameters 124, patient turndata 126, and optional patient data 128 are presented on the display120. In particular, information of greater interest or importance to theclinician may be displayed in larger format and may also be displayed inboth numerical and graphical formats to convey the current measurementas well as the historical trend of measurements for a period of time,such as, for example, the preceding hour.

As illustrated by dotted lines in FIG. 1B, the display 130 of theportable patient monitor 130 is an optional feature of the patientmonitor 106 which may be configured to present patient physiologicaldata 134, patient turn data 136, and additional, optional patient data138.

FIG. 1C is a simplified functional block diagram of an embodiment of thedisclosed patient monitoring system 100. The system includes thepatient-worn wireless sensor 102 having one or more sensors, a wirelesscommunications link 104, through which sensor data from the wirelesssensor 102 accesses the patient data processing environment 105 whichincludes a patient monitor 106, a communications network 108, amulti-patient monitoring system 110, a hospital or facility informationsystem 112, one or more nurses' station systems 113, and one or moreclinician devices 114. An artisan will appreciate that numerous othercomputing systems, servers, processing nodes, display devices, printers,and the like can be included in the disclosed patient monitoring system100.

The wireless sensor 102 is worn by a patient who has been determined tobe at risk of forming one or more pressure ulcers, e.g., a patient whois confined to bed for an extended period of time. The wireless sensor102 is capable of monitoring on a continuous or periodic (e.g., everysecond) basis the orientation of the patient to help determine whetherthe patient is repositioned frequently enough to reduce the patient'srisk of forming a pressure ulcer. In certain embodiments, the wirelesssensor 102 minimally processes measured acceleration and/or angularvelocity data and wirelessly transmits the minimally-processed data tothe patient monitor 106 by way of the wireless communications link 104.

The wireless sensor 102 and the patient monitor 106 can be configured toutilize different wireless technologies to form the wirelesscommunications link 104. In certain scenarios, it may be desirable totransmit data over Bluetooth or ZigBee, for example, when the distancebetween the wireless sensor 102 and the patient monitor 106 is withinrange of Bluetooth or ZigBee communication. Transmitting data usingBluetooth or ZigBee is advantageous because these technologies requireless power than other wireless technologies. Accordingly, longevity ofembodiments of the disclosed wireless sensor 102 using batteries may beincreased by using Bluetooth or ZigBee protocols.

In other scenarios, it may be desirable to transmit data using Wi-Fi orcellular telephony, for example, when the distance between the wirelesssensor 102 and the patient monitor 106 is out of range of communicationfor Bluetooth or ZigBee. A wireless sensor 102 may be able to transmitdata over a greater distance using Wi-Fi or cellular telephony thanother wireless technologies. In still other scenarios, it may bedesirable to transmit data using a first wireless technology and thenautomatically switching to a second wireless technology in order tomaximize data transfer and/or energy efficiency.

In some embodiments, the wireless sensor 102 automatically transmitsdata over Bluetooth or ZigBee when the wireless sensor 102 is within apre-determined distance from the bedside patient monitor 106. Thewireless sensor 102 automatically transmits data over Wi-Fi or cellulartelephony when the wireless sensor 102 is beyond a pre-determineddistance away from the bedside patient monitor 106. In certainembodiments, the wireless sensor 102 can automatically convert fromBluetooth or ZigBee to Wi-Fi or cellular telephony, and vice versa,depending on the distance between the wireless sensor 102 and thebedside patient monitor 106.

In some embodiments, the wireless sensor 102 automatically transmitsdata over Bluetooth or ZigBee when the Bluetooth or ZigBee signalstrength is sufficiently strong or when there is interference with Wi-Fior cellular telephony. The wireless sensor 102 automatically transmitsdata over Wi-Fi or cellular telephony when the Bluetooth or ZigBeesignal strength is not sufficiently strong. In certain embodiments, thewireless sensor 102 can automatically convert from Bluetooth or ZigBeeto Wi-Fi or cellular telephony, and vice versa, depending on signalstrength.

The patient monitor 106 can be operable to receive, store and processthe measured acceleration and angular velocity data transmitted by thewireless sensor 102 to determine the patient's orientation. Oncedetermined, the patient monitor 106 can display the patient's currentorientation. In some embodiments, the patient monitor 106 displays thepatient's current orientation along with the patient's previousorientations over time, thereby providing the user the ability to view ahistorical record of the patient's orientation. In certain embodiments,e.g., as illustrated in FIGS. 13A-F and 14, the patient orientation isdisplayed by icons, such stick figures, enabling the clinician toreadily understand the patient's present positional state and thepatient's positional history. The patient monitor 106 can also beconfigured to keep track of the length of time the patient remains in aparticular orientation. In some embodiments the patient monitor 106displays the amount of time the patient has been in the currentorientation. Additionally, the patient monitor 106 can determine whenthe patient remains in a particular orientation for a duration greaterthan that prescribed by a clinician according to a repositioningprotocol. Under such conditions, the patent monitor 106 can issuealarms, alerts, and/or notifications to the patient and/or to caregiversindicating that the patient should be repositioned to adhere to theprescribed repositioning protocol to reduce the risk of pressure ulcerformation.

As illustrated in FIG. 1C, the patient monitor 106 communicates over anetwork 108 with a patient data processing environment 105 that includesa multi-patient monitoring system 110, a hospital/facility system 112,nurses' station systems 113, and clinician devices 114. Examples ofnetwork-based clinical processing environments, including multi-patientmonitoring systems 110, are disclosed in U.S. Pat. Pub. Nos.2011/0105854, 2011/0169644, and 2007/0180140, which are incorporatedherein by reference in their entirety. In general, the multi-patientmonitoring system 110 communicates with a hospital/facility system 112,the nurses' station systems 113, and clinician devices 114. Thehospital/facility system 112 can include systems such as electronicmedical record (EMR) and/or and admit, discharge, and transfer (ADT)systems. The multi-patient monitoring system 110 may advantageouslyobtain through push, pull or combination technologies patientinformation entered at patient admission, such as patient identityinformation, demographic information, billing information, and the like.The patient monitor 106 can access this information to associate themonitored patient with the hospital/facility systems 112. Communicationbetween the multi-patient monitoring system 110, the hospital/facilitysystem 112, the nurses' station systems 113, the clinician devices 114,and the patient monitor 106 may be accomplished by any techniquerecognizable to an artisan from the disclosure herein, includingwireless, wired, over mobile or other computing networks, or the like.

FIG. 1D is a simplified functional block diagram of the disclosedpatient monitoring system 100 of FIG. 1C expanded to illustrate use ofmultiple wireless sensors 102 with multiple patients within a caretakingenvironment. Advantageously, the patient monitoring system 100 canprovide individual patient information on, for example, a patientmonitor 106, as well as aggregated patient information on, for example,a nurses' station server or system 114. Thus a caretaker can have anoverview of positional information corresponding to a population ofpatients located, for example, in a hospital floor or unit.

In some circumstances, there may not be the need, desire, or resourcesavailable to employ a bedside patient monitor 106 associated with awireless sensor 102 being worn by a patient. For example, the clinicalenvironment might be staffed such that patient data are collected,analyzed, displayed, and monitored at a central observation station,such as a nurses' station, rather than at the patient's bedside.Moreover, when the information is to be accessed by a clinician at thebedside, portable clinician devices 114, such as, for example, tablets,PDAs or the like, may be used by caregivers to access the requiredpatient-specific information while at the patient's bedside.

In such situations, as illustrated in FIGS. 1E and 1F, the wirelesssensor 102 can communicate to the various systems of the clinicalcomputing environment by way of a signal extender/repeater 107. Theextender/repeater 107 is located within range of the wireless sensor 102(e.g., near the patient's bed 118) and configured to relay data, via thenetwork 108, between the wireless sensor 102 and one or more computingsystems capable of processing, storing, displaying, and/or transmittingthe data collected by the wireless sensor 102. Advantageously, arelatively low cost extender/repeater 107 can be used to receive signalstransmitted from one or more wireless sensors 102 over the wirelesscommunications link(s) 104 using a shorter-range, lower-power-consumingtransmission mode, such as for example, Bluetooth or ZigBee. Theextender/repeater 107 can then retransmit the received signals to one ormore computing systems in the patient data processing environment 105over the network 108. In accordance with some embodiments, theextender/repeater 107 is a Bluetooth-to-Ethernet gateway thatretransmits signals received from the wireless sensor 102 to computingnodes, such as, for example, the multi-patient monitoring system 110,over the network 108. In some embodiments, the extender/repeater 107 isa Bluetooth-to-WiFi bridge that provides access to the network 108 forthe wireless sensor 102. Of course, a skilled artisan will recognizethat there are numerous ways to implement the extender/repeater 107.

FIG. 2A illustrates a simplified hardware block diagram of an embodimentof the disclosed wireless sensor 102. As shown in FIG. 2A, the wirelesssensor 102 can include a processor 202, a data storage device 204, awireless transceiver 206, a system bus 208, an accelerometer 210, agyroscope 212, a battery 214, and an information element 215. Theprocessor 202 can be configured, among other things, to process data,execute instructions to perform one or more functions, such as themethods disclosed herein, and control the operation of the wirelesssensor 102. The data storage device 204 can include one or more memorydevices that store data, including without limitation, random accessmemory (RAM) and read-only memory (ROM). The wireless transceiver 206can be configured to use any of a variety of wireless technologies, suchas Wi-Fi (802.11x), Bluetooth, ZigBee, cellular telephony, infrared,RFID, satellite transmission, proprietary protocols, combinations of thesame, and the like. The components of the wireless sensor 102 can becoupled together by way of a system bus 208, which may represent one ormore buses. The battery 214 provides power for the hardware componentsof the wireless sensor 102 described herein. As illustrated in FIG. 2A,the battery 214 communicates with other components over system bus 208.One skilled in the art will understand that the battery 214 cancommunicate with one or more of the hardware functional componentsdepicted in FIG. 2A by one or more separate electrical connections. Theinformation element 215 can be a memory storage element that stores, innon-volatile memory, information used to help maintain a standard ofquality associated with the wireless sensor 102. Illustratively, theinformation element 215 can store information regarding whether thesensor 102 has been previously activated and whether the sensor 102 hasbeen previously operational for a prolonged period of time, such as, forexample, four hours. The information stored in the information element215 can be used to help detect improper re-use of the wireless sensor102.

In some embodiments, the accelerometer 210 is a three-dimensional (3D)accelerometer. The term 3D accelerometer as used herein includes itsbroad meaning known to a skilled artisan. The accelerometer 210 providesoutputs responsive to acceleration of the wireless sensor 102 in threeorthogonal axes, sometimes denoted as the “X,” “Y,” and “Z” axes. Anaccelerometer 210 may measure acceleration that it experiences relativeto Earth's gravity. An accelerometer 210 may provide accelerationinformation along three axes, and it and may provide accelerationinformation which is the equivalent of inertial acceleration minus localgravitational acceleration. Accelerometers 210 are well known to thoseskilled in the art. The accelerometer 210 may be amicro-electromechanical system (MEMS), and it may includepiezo-resistors, among other forms of implementation. The accelerometer210 may be a high-impedance charge output or a low-impedance chargeoutput accelerometer 210. In some embodiments, the accelerometer 210 maybe a tri-axis accelerometer, and the output of the accelerometer 210 mayinclude three signals, each of which represents measured acceleration inparticular axis. The output of the accelerometer 210 may be 8-bit,12-bit, or any other appropriate-sized output signal. The outputs of theaccelerometer may be in analog or digital form. The accelerometer 210may be used to determine the position, orientation, and/or motion of thepatient to which the wireless sensor 102 is attached.

In some embodiments, the gyroscope 212 is a three-axis digital gyroscopewith angle resolution of two degrees and with a sensor drift adjustmentcapability of one degree. The term three-axis gyroscope as used hereinincludes its broad meaning known to a skilled artisan. The gyroscope 212provides outputs responsive to sensed angular velocity of the wirelesssensor 102 (as affixed to the patient) in three orthogonal axescorresponding to measurements of pitch, yaw, and roll. A skilled artisanwill appreciate that numerous other gyroscopes 212 can be used in thewireless sensor 102 without departing from the scope of the disclosureherein. In certain embodiments, the accelerometer 210 and gyroscope 212can be integrated into a single hardware component which may be referredto as an inertial measurement unit (IMU). In some embodiments, the IMUcan also include an embedded processor that handles, among other things,signal sampling, buffering, sensor calibration, and sensor fusionprocessing of the sensed inertial data. In other embodiments, theprocessor 202 can perform these functions. And in still otherembodiments, the sensed inertial data are minimally processed by thecomponents of the wireless sensor 102 and transmitted to an externalsystem, such as the patient monitor 106, for further processing, therebyminimizing the complexity, power consumption, and cost of the wirelesssensor 102, which may be a single-use, disposable product.

FIG. 2B is a simplified hardware functional block diagram of anembodiment of the disclosed wireless sensor 102 that includes thefollowing optional (as reflected by dotted lines) sensing components: amagnetometer 216 which may also be referred to as a compass, atemperature sensor 218, an acoustic respiration sensor 220, anelectrocardiogram (ECG) sensor 222, one or more oximetry sensors 224, amoisture sensor 226, and an impedance sensor 228. In some embodiments,the magnetometer 216 is a three-dimensional magnetometer that providesinformation indicative of magnetic fields, including the Earth'smagnetic field. While depicted in FIG. 2B as separate functionalelements, a skilled artisan will understand that the accelerometer 210,gyroscope 212, and magnetometer 214 can be integrated into a singlehardware component such as an inertial measurement unit.

According to an embodiment, a system and method are described herein tocalculate three-dimensional position and orientation of an objectderived from inputs from three sensors attached to the object: anaccelerometer 210 configured to measure linear acceleration along threeaxes; a gyroscope 212 configured to measure angular velocity aroundthree axes; and a magnetometer 214 configured to measure the strength ofa magnetic field (such as the Earth's magnetic field) along three axes.In an embodiment, the three sensors 210, 212, and 214 are attached tothe wireless sensor 102 which is affixed to the patient. According to anembodiment, the sensors 210, 212, and 214 are sampled at a rate betweenapproximately 10 Hz and approximately 100 Hz. One skilled in the artwill appreciate that the sensors 210, 212, and 214 can be sampled atdifferent rates without deviating from the scope of the presentdisclosure. The sampled data from the three sensors 210, 212, and 214,which provide nine sensor inputs, are processed to describe thepatient's position and orientation in three-dimensional space. In anembodiment, the patient's position and orientation are described interms of Euler angles as a set of rotations around a set of X-Y-Z axesof the patient.

Also illustrated in FIG. 2B is a temperature sensor 218 which may beused to measure the patient's body core temperature which is a vitalsign used by clinicians to monitor and manage patients' conditions. Thetemperature sensor 218 can include a thermocouple, atemperature-measuring device having two dissimilar conductors orsemiconductors that contact each other at one or more spots. Atemperature differential is experienced by the different conductors. Thethermocouple produces a voltage when the contact spot differs from areference temperature. Advantageously, thermocouples are self-poweredand therefore do not require an external power source for operation. Inan embodiment, the temperature sensor 218 includes a thermistor. Athermistor is a type of resistor whose resistance value varies dependingon its temperature. Thermistors typically offer a high degree ofprecision within a limited temperature range.

The acoustic respiration sensor 220 can be used to sense vibrationalmotion from the patient's body (e.g., the patient's chest) that areindicative of various physiologic parameters and/or conditions,including without limitation, heart rate, respiration rate, snoring,coughing, choking, wheezing, and respiratory obstruction (e.g., apneicevents). The ECG sensor 222 can be used to measure the patient's cardiacactivity. According to an embodiment, the ECG sensor 222 includes twoelectrodes and a single lead. The oximetry sensor(s) 224 can be used tomonitor the patient's pulse oximetry, a widely accepted noninvasiveprocedure for measuring the oxygen saturation level of arterial blood,an indicator of a person's oxygen supply. A typical pulse oximetrysystem utilizes an optical sensor clipped onto a portion of thepatient's body (such as, for example, a fingertip, an ear lobe, anostril, and the like) to measure the relative volume of oxygenatedhemoglobin in pulsatile arterial blood flowing within the portion of thebody being sensed. Oxygen saturation (SpO2), pulse rate, aplethysmograph waveform, perfusion index (PI), pleth variability index(PVI), methemoglobin (MetHb), carboxyhemoglobin (CoHb), total hemoglobin(tHb), glucose, and/or otherwise can be measured and monitored using theoximetry sensor(s) 224. The moisture sensor 226 can be used to determinea moisture content of the patient's skin which is a relevant clinicalfactor in assessing the patient's risk of forming a pressure ulcer. Theimpedance sensor 228 can be used to track fluid levels of the patient.For example, the impedance sensor 228 can monitor and detect edema,heart failure progression, and sepsis in the patient.

FIG. 3A is a schematic exploded perspective view of an embodiment of thedisclosed wireless sensor 102 including a bottom base 310, a removablebattery isolator 320, a mounting frame 330, a circuit board 340, ahousing 350, and a top base 360. The bottom base 310 is a substratehaving a top surface on which various components of the wireless sensor102 are positioned, and a bottom surface that is used to affix thewireless sensor 102 to the patient's body. The bottom base 310 and topbase 360 can be made of medical-grade foam material such as whitepolyethylene, polyurethane, or reticulated polyurethane foams, to name afew. As illustrated in the embodiment illustrated in FIG. 3A, the bottombase 310 and the top base 360 are each in a substantially oval shape,with a thickness of approximately 1 mm. The top base 360 includes acut-out 362 through which the housing 350 fits during assembly. Ofcourse, a skilled artisan will understand that there are numerous sizesand shapes suitable for the top and bottom bases 310 and 360 that can beemployed without departing from the scope of the present disclosure. Thebottom surface of the bottom base 310 is coated with a high tack,medical-grade adhesive, which when applied to the patient's skin, issuitable for long-term monitoring, such as, for example two days orlonger. Portions of the top surface of the bottom base 310 are alsocoated with a medical-grade adhesive, as the bottom base 310 and the topbase 360 are adhered together during assembly of the wireless sensor102.

The removable battery isolator 320 is a flexible strip made of anelectrically insulating material that serves to block electricalcommunication between the battery 214 and an electrical contact (notshown) on the circuit board 340. The battery isolator 320 is used topreserve battery power until the wireless sensor 102 is ready for use.The battery isolator 320 blocks electrical connection between thebattery 214 and the circuit board 340 until the battery isolator 320 isremoved from the wireless sensor 102. The battery isolator 320 can bemade of any material that possesses adequate flexibility to be slidablyremoved from its initial position and adequate dielectric properties soas to electrically isolate the battery from the circuit board 340. Forexample, the battery isolator can be made of plastic, polymer film,paper, foam, combinations of such materials, or the like. The batteryisolator 320 includes a pull tab 322 that extends through a slot 352 ofthe housing 350 when the wireless sensor 102 is assembled. The pull tab322 can be textured to provide a frictional surface to aid in grippingand sliding the pull tab 322 out of its original assembled position.Once the battery isolator 320 is removed the battery 214 makes anelectrical connection with the battery contact to energize theelectronic components of the wireless sensor 102.

The mounting frame 330 is a structural support element that helps securethe battery 214 to the circuit board 340. The mounting frame 340 haswings 342 that, when assembled are slid between battery contacts 342 andthe battery 214. Additionally, the mounting frame 330 serves to providerigid structure between the circuit board 340 and the bottom base 310.According to some embodiments that include an acoustic respiratorysensor, the rigid structure transmits vibrational motion (vibrations)emanating from the patient (such as, for example, vibrational motionsrelated to respiration, heartbeat, snoring, coughing, choking, wheezing,respiratory obstruction, and the like) to the accelerometer 210positioned on the circuit board 340.

The circuit board 340, which may also be referred to herein as asubstrate layer 340 and a circuit layer 340, mechanically supports andelectrically connects electrical components to perform many of thefunctions of the wireless sensor 102. The circuit board 340 includesconduction tracks and connection pads. Such electrical components caninclude without limitation, the processor 202, the storage device 204,the wireless transceiver 206, the accelerometer 210, the gyroscope 212,the magnetomer 214, the temperature sensor 218, the acoustic respirationsensor 220, the ECG sensor 222, the oximetry sensor 224, the moisturesensor 226, and the impedance sensor 228. In an embodiment, the circuitboard 340 is double sided having electronic components mounted on a topside and a battery contact (not shown) on a bottom side. Of course askilled artisan will recognize other possibilities for mounting andinterconnecting the electrical and electronic components of the wirelesssensor 102.

As illustrated in FIG. 3A, a battery holder 342 is attached to two sidesof the top portion circuit board 340 and extends (forming a supportstructure) under the bottom side of the circuit board 340 to hold thebattery 214 in position relative to the circuit board 340. The batteryholder 342 is made of electrically conductive material. In someembodiments, the battery 214 is a coin cell battery having a cathode onthe top side and an anode on the bottom side. Electrical connectionbetween the anode of the battery 214 and the circuit board 340 is madeby way of the battery holder which is in electrical contact with theanode of the battery 214 and the circuit board 340. The cathode of thebattery 214 is positioned to touch a battery contact (not shown) on thebottom side of the circuit board 340. In some embodiments, the batterycontact includes a spring arm that applies force on the battery contactto ensure that contact is made between the anode of the battery 214 andthe battery contact. During assembly and prior to use, the batteryisolator 320 is inserted between the anode of the battery 214 and thebattery connector to block electrical contact.

The housing 350 is a structural component that serves to contain andprotect the components of the wireless sensor 102. The housing 350 canbe made of any material that is capable of adequately protecting theelectronic components of the wireless sensor 102. Examples of suchmaterials include without limitation thermoplastics and thermosettingpolymers. The housing 350 includes a slot 352 through which the batteryisolator 320 is inserted during assembly. The housing 350 also includesa rim 354 that extends around the outer surface of the housing 350. Therim 354 is used to secure the housing 350 in position relative to thebottom base 310 and the top base 360 when the wireless sensor 102 isassembled.

Assembly of the wireless sensor 102 is as follows: The circuit board 340and battery holder 342 holding the battery 214 are placed into thehousing 350. The wings 332 of the mounting frame 330 are inserted inbetween the battery 214 and the battery holder 342, so as to align themounting frame 330 with the circuit board 340. The battery isolator 320is then positioned between the battery contact and the battery 214. Thepull tab 322 of the battery isolator 320 is then fed through the slot352 in the housing 350. The top base 360 is then positioned over thehousing 350, which now houses the assembled circuit board 340, batteryholder 342, battery 214, mounting frame 330, and battery isolator 320,using the cut-out 362 for alignment. The rim 354 of the housing 350adheres to the bottom surface of the top base 360, which is coated withhigh tack, medical-grade adhesive. The partial assembly, which nowincludes the top base 360, the housing 350, the circuit board 340, thebattery holder 342, the battery 214, the mounting frame 330, and thebattery isolator 320, is positioned centrally onto the top surface ofthe bottom base 310, aligning the edges of the base top 360 with theedges of the base bottom 310. In some embodiments, a coupon (or diecutting tool) is used to cut away excess portions of the now combinedtop and bottom bases 360 and 310 to form a final shape of the wirelesssensor 102. The bottom surface of the bottom base 310 is then coatedwith a high tack, medical-grade adhesive, and a release liner (notshown) is placed on the bottom surface of the bottom base 3310 toprotect the adhesive until it is time for use.

A schematic perspective view of the assembled wireless sensor 102 isillustrated in FIG. 3B. Also illustrated in FIG. 3B is a button/switch324 located on a top portion of the housing 350. The button/switch 324can be used to change modes of the wireless sensor 102. For example, insome embodiments, pressing and holding the button/switch 324 can causethe wireless sensor 102 to switch into a pairing mode of operation. Thepairing mode is used to associate the wireless sensor 102 with a patientmonitor 106 or with an extender/repeater 107. FIG. 3C provides aschematic side view of an embodiment of the assembled wireless sensor102 with cross-section line A-A identified.

Referring now to FIGS. 4A and 4B, an embodiment of the wireless sensor102 is disclosed which includes a temperature sensor 218. FIG. 4A is aschematic cross-sectional view, sectioned along line A-A of FIG. 3C,illustrating an assembled embodiment of the disclosed wireless sensor102 which includes the temperature sensor 218. For easier visibility,the battery isolator 320 and the battery holder 342 are not illustrated.FIG. 4B is a schematic bottom view of the embodiment of the disclosedwireless sensor of FIG. 4A. The bottom surface of the bottom base 310 isillustrated. Also illustrated in phantom (i.e., dotted lines) is theoutline of cut-out 362 which also indicates the position of the housing350 in relation to the bottom surface of the bottom base 310.

As explained above with respect to the assembly of the wireless sensor102, the top surface of the bottom base 310 is in contact with andadhered to the bottom surface of the top base 360. The rim 354 of thehousing 350 is sandwiched between the two bases 310 and 360 to securethe housing 350. The housing 350 also protrudes through the cut-out 362of the top base 360. Within the housing, the battery 214 and themounting frame 330 are adjacent the top surface of the bottom base 310.

As illustrated in FIG. 4A, the temperature sensor 218 is mounted on thecircuit board 340. To perform its temperature sensing function, thetemperature sensor 218 is in thermal contact with the patient's skin. Toachieve this, structure to transmit thermal energy from the patient'sbody to the temperature sensor 218 is provided. In particular, inputs tothe temperature sensor 218 are thermally connected to multiplethrough-hole vias 410 located in the circuit board 340. A through-holevia is a small vertical opening or pathway in the circuit board 340through which thermally and/or electrically conductive material can beplaced, thereby permitting transmission of thermal and/or electricalenergy from one side of the circuit board 340 to the other side. Underthe through-hole vias 410 is an aperture or opening 404 which extendsthrough the mounting frame 330 (to form a mounting frame aperture) andthrough the bottom base 310 of the wireless sensor 102. The aperture 404provides access from the temperature sensor 218 to the patient's skinwhen the wireless sensor 102 is worn by the patient. The aperture 404and the through-hole vias 410 are filled with thermally conductivematerial 402. Thermally conductive materials are well known in the artand can include, by way of non-limiting example, thermally conductiveelastomers, polymers, and resins, to name a few. Illustratively, inoperation, the wireless sensor 102 is affixed to the patient's skin. Thethermally conductive material 402, exposed to the patient's skin,transmits thermal energy from the patient's body through the aperture404 and the through-hole vias 410 to arrive at the inputs to thetemperature sensor 218.

Advantageously, the disclosed wireless sensor 102 can measure thepatient's body core temperature (an established and useful vital sign)with the temperature sensor 218 using a technique by which deep tissuetemperature can be measured from the skin surface. In the human body,there is a natural heat flux between the body core and the skin surfacebecause the body core temperature is typically at a higher temperaturethan that of the skin surface. Thus heat flows from the body core to theskin. By insulating the skin surface at and around the point at whichthe skin temperature is measured—thereby blocking heat from escaping—thetemperature gradient between the body core and the skin surface willdecrease. The skin temperature, under the insulated area will rise untilit reaches equilibrium with the warmest region (i.e., the body core)under the insulation, thereby approaching the body core temperature.When equilibrium is reached, the skin temperature is equal to the corebody temperature. Advantageously, the bottom base 310 and top base 360of the wireless sensor 102, which are in contact with the patient's skinaround the temperature sensor 218, possess thermal insulationproperties. Illustratively, by way of non-limiting example, the bottombase 310 and top base 360 can be made thermally insulating materialsincluding polyurethane foam, polystyrene foam, neoprene foam, neoprenerubber, polyester (Mylar), polytetrafluoroethylene (PTFE), siliconefoam, silicone rubber, or the like. Accordingly, the temperature sensor218 can measure the patient's body core temperature.

FIG. 4C is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 4A and 4B. As shown, thetemperature sensor 218 is mounted on the top surface of the circuitboard 340. The aperture 404 extends through the mounting frame 330 andthe bottom base 310 and is aligned vertically with the through-hole vias410 (not shown in FIG. 4C) and the temperature sensor 218. The aperture404 and the through-hole vias 410 are filled with thermally conductivematerial 402. Thus the disclosed structure provides thermal connectivitybetween the patient's skin and the temperature sensor 218.

Referring now to FIGS. 5A and 5B, an embodiment of the wireless sensor102 is disclosed which includes an acoustic respiration sensor 220. FIG.5A is a schematic cross-sectional view, sectioned along line A-A of FIG.3C, illustrating an assembled embodiment of the disclosed wirelesssensor 102 which includes the acoustic respiration sensor 220. Foreasier visibility, the battery isolator 320 and the battery holder 342are not illustrated. FIG. 5B is a schematic bottom view of theembodiment of the disclosed wireless sensor of FIG. 5A. The bottomsurface of the bottom base 310 is illustrated. Also illustrated inphantom (i.e., dotted lines) is the outline of cut-out 362 whichindicates the position of the housing 350 in relation to the bottomsurface of the bottom base 310.

As illustrated in FIG. 5A, the acoustic respiration sensor 220 ismounted underneath the battery 214. Operationally, the acousticrespiration sensor 220 detects vibratory motion emanating from thepatient's body (e.g., the patient's chest) and mechanically transmitsthe detected vibratory motion to the accelerometer 210. Theaccelerometer 210 senses the mechanically transmitted vibratory motion.The signal collected by accelerometer 210 can be processed to extractthe vibratory motion from other sensed acceleration signals. Examples ofsuch vibratory motion can include, without limitation, heart beats,respiration activity, coughing, wheezing, snoring, choking, andrespiratory obstruction (e.g., apneic events). To mechanically transmitthe sensed vibratory motion effectively, the acoustic respiration sensor220 is in rigid structural contact with the accelerometer 210. Toachieve this, the acoustic respiration sensor 220 is mounted to thebottom side of the battery 214. In particular, the acoustic respirationsensor 220 includes a rim 221 that is sandwiched between the bottomsurface of the battery 214 and the bottom base 310. Accordingly, the rim221 serves to rigidly secure the acoustic respiration sensor 220 to thebottom surface of the battery 214.

As illustrated in FIG. 5A, the acoustic respiration sensor 220 protrudesthrough an aperture or opening 502 in the bottom base 310, beyond theplane created by the bottom base 310. This is to ensure that theacoustic respiration sensor 220 is in direct contact with the patient'sbody (e.g., chest) so as to sense the vibrational motion emanating fromthe patient. Within the acoustic respiration sensor 220 is a flexiblewire or other such structure under slight tension such that when thewire is exposed to vibratory motion, it will vibrate in a manner that isproportional to the sensed vibratory motion with respect to bothfrequency and magnitude of the sensed vibratory motion. The acousticrespiration sensor 220 is configured to transmit the sensed vibratorymotion through rigid structures of the wireless sensor 102 such that thetransmitted vibratory motion is sensed by the accelerometer 210. Therigid structure includes the battery 214 and the circuit board 340.

FIG. 5C is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 5A-B. As shown, the accelerometer210 is mounted on the top surface of the circuit board 340 over thebattery 214 which is secured underneath the circuit board 340. Theacoustic respiration sensor 220 (not shown in FIG. 5C) fits between thebattery 214 and the bottom base 310. The aperture 502 extends throughthe bottom base 310 and is aligned vertically with battery 214 such thatthe acoustic respiration sensor 220 is secured to rigid structure of thewireless sensor 102. Thus the disclosed structure provides the abilityfor the acoustic respiration sensor 220 to mechanically transmitvibratory motion from the patient's chest to the accelerometer 210.

FIGS. 6A-C illustrate an embodiment of the disclosed wireless sensor 102which includes a temperature sensor 218 and an acoustic respirationsensor 220. FIG. 6A is a schematic cross-sectional view, sectioned alongline A-A of FIG. 3C, illustrating an assembled embodiment of thedisclosed wireless sensor 102 which includes the temperature sensor 218and acoustic respiration sensor 220. For easier visibility, the batteryisolator 320 and the battery holder 342 are not illustrated. FIG. 6B isa schematic bottom view of the embodiment of the disclosed wirelesssensor of FIG. 6A. FIG. 6C is a schematic exploded perspective view ofthe embodiment of the disclosed wireless sensor 102 of FIGS. 6A and 6B.

Structurally, the embodiment depicted in FIGS. 6A-C is a combination ofthe embodiments depicted in FIGS. 4A-C and 5A-C. As illustrated in FIGS.6A-B, the temperature sensor 218 is mounted on the circuit board 340. Aspreviously described, inputs to the temperature sensor 218 are thermallycoupled to multiple through-hole vias 410 located in the circuit board340. Under the through-hole vias 410 is an aperture 404 which extendsthrough the mounting frame 330 and through the bottom base 310 of thewireless sensor 102. The aperture 404 provides access from thetemperature sensor 218 to the patient's skin when the wireless sensor102 is worn by the patient. The aperture 404 and the through-hole vias410 are filled with thermally conductive material 402. In operation, thewireless sensor 102 is affixed to the patient's skin. The thermallyconductive material 402, exposed to the patient's skin, transmitsthermal energy from the patient's body through the aperture 404 and thethrough-hole vias 410 to arrive at the inputs to the temperature sensor218.

Also as illustrated in FIGS. 6A-B, the acoustic respiration sensor 220is mounted underneath the battery 214. In particular, the acousticrespiration sensor 220 includes rim 221 that is sandwiched between thebottom surface of the battery 214 and the bottom base 310. Accordingly,the rim 221 serves to rigidly secure the acoustic respiration sensor 220to the bottom surface of the battery 214. The acoustic respirationsensor 220 protrudes through the aperture 502 in the bottom base 310,beyond the plane created by the bottom base 310. The acousticrespiration sensor 220 is configured to transmit vibratory motion sensedfrom the patient (e.g., from the patient's chest) through rigidstructures of the wireless sensor 102 such that the transmittedvibratory motion is sensed by the accelerometer 210. The rigid structureincludes the battery 214 and the circuit board 340.

FIG. 6C is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 6A and 6B. As shown, thetemperature sensor 218 is mounted on the top surface of the circuitboard 340. The aperture 404 extends through the mounting frame 330 andthe bottom base 310 and is aligned vertically with the through-hole vias410 (not shown in FIG. 4C) and the temperature sensor 218. The aperture404 and the through-hole vias 410 are filled with thermally conductivematerial 402. Additionally, the accelerometer 210 is mounted on the topsurface of the circuit board 340 over the battery 214 which is securedunderneath the circuit board 340. The acoustic respiration sensor 220(not shown in FIG. 6C) fits between the battery 214 and the bottom base310. In some embodiments, the acoustic respiration sensor 220 abutsagainst the mounting frame 330 in a manner such that the acousticrespiration sensor 220, the mounting frame 330, the battery 214 and thecircuit board 340 form a rigid structure capable of mechanicallytransmitting vibratory motion sensed by the acoustic respiration sensor220 to the accelerometer 210 mounted on the circuit board 340. Theaperture 502 extends through the bottom base 310 and is alignedvertically with battery 214 such that the acoustic respiration sensor220 is secured to rigid structure of the wireless sensor 102. Thus thedisclosed embodiment provides thermal connectivity between the patient'sskin and the temperature sensor 218 and the ability for the acousticrespiration sensor 220 to mechanically transmit vibratory motion fromthe patient's chest to the accelerometer 210.

Advantageously, the embodiment disclosed in FIGS. 6A-C is capable ofproviding, among other things, three vital signs: body core temperature,pulse rate, and respiration rate. Vital signs are measurements of thebody's most basic functions and are used routinely by healthcareproviders to assess and monitor a patient's status. The patient's bodycore temperature can be provided by the temperature sensor 218. Thepatient's pulse rate and respiration rate can be provided by theacoustic respiration sensor 220 in combination with the accelerometer210.

Referring to FIGS. 7A-F, an embodiment of the disclosed wireless sensor102 is shown which includes an electrocardiogram (ECG) sensor 222.Chip-scale and/or component-scale ECG sensors, suitable for mounting oncircuit boards are known in the art. Illustratively, by way ofnon-limiting example, solid state ECG sensors are offered by TexasInstruments and by Plessy Semiconductors Ltd., to name a few. FIG. 7A isa perspective view of the embodiment of the disclosed patient-wornwireless sensor 102 having an ECG sensor 222 including an ECG lead 706that extends from the housing 350. The wireless sensor 102 is adhered tothe patient's chest, for example, over the manubrium as illustrated inFIG. 7A. The ECG lead 706 extends from the housing 350 of the wirelesssensor 102 to a location on the patient's chest suitable to senseelectrical signals generated by the patient's heart. The ECG lead 706 isin electrical communication with an ECG electrode 707 which, inoperation, is adhered to the patient's chest. In certain embodiments,the ECG electrode 707 includes conducting gel embedded in the middle ofa self-adhesive pad. The ECG electrode 707 the senses electrical signalsfrom the patient's chest and transmits the sensed signals, via the lead706, to the ECG sensor 222. The electrode 707 adheres to the patient'sskin and senses electrical signals therefrom. A skilled artisan willappreciate that many structures, forms, and formats of ECG electrodesare well known in the art and can be used to implement the ECG electrode707.

As illustrated in FIG. 7A, the ECG lead 706 extends to the left side ofthe patient's chest to a position across the heart from where thewireless sensor 102 is located. Another ECG electrode 702 (describedbelow), also in contact with the patient's skin, is formed beneath thehousing 350 at the bottom base 310. Thus, a vector is formed between theECG lead electrode 707 and the ECG electrode 702 by which the electricalsignals of the patient's heart can be sensed. Illustratively, when theelectrodes 702 and 707 are positioned as depicted in FIG. 7A, the ECGsensor 222 can sense ECG signals that are similar in morphology to ECGsignals detected on Lead I or Lead II of a standard 12-lead ECG.

FIG. 7B is a schematic assembled perspective view of the embodiment ofthe disclosed wireless sensor 102 of FIG. 7A. The ECG lead 706 isconnected to the ECG sensor 222 (shown in FIG. 7D) which is mounted onthe circuit board 340. As illustrated in FIG. 7B, the ECG lead extendsthrough the housing 350 to a lockable retractable reel 708 that storesthe ECG lead 706 in a coil when not in use. The ECG lead 706 can beextended from the reel 708 and locked in the desired position, therebyenabling placement of the ECG lead electrode 707 at a desired locationon the patient's chest. In some embodiments, the locking mechanism isengaged and disengaged by applying a pulling force on the lead 706.Various forms and versions of lockable retractable reels are well knownin the art and may be used to implement the reel 708.

FIG. 7C provides a schematic side view of the embodiment of theassembled wireless sensor 102 of FIGS. 7A and 7B with cross-section lineB-B identified. FIG. 7D is a cross-sectional view of the embodiment ofFIGS. 7A-C sectioned along line B-B. As illustrated in FIG. 7D, the ECGsensor 222 is mounted on the circuit board 340. To perform its sensingfunction, the ECG sensor 222 is in electrical contact with at least twopoints on the patient's skin. Two electrodes 702 and 707 are provided toachieve this purpose. While ECG electrode 707 has been described above,description of the ECG electrode 702 follows herewith.

ECG electrode 702 is located within the bottom base 310 of the wirelesssensor 102. An input to the ECG sensor 222 is electrically connected tomultiple through-hole vias 710 located in the circuit board 340. Aspreviously described, through-hole vias are small vertical openings, orpathways, in the circuit board 340 through which electrically conductivematerial can be placed, thereby permitting transmission of electricalsignals from one side of the circuit board 340 to the other side. Underthe through-hole vias 710 is an aperture or opening 704 which extendsthrough the mounting frame 330 (to form a mounting frame aperture) andthrough the bottom base 310 of the wireless sensor 102. The aperture 704provides access from the ECG sensor 222 to the patient's skin when thewireless sensor 102 is worn by the patient. The aperture 704 and thethrough-hole vias 710 are filled with electrically conductive materialto form the ECG electrode 702. Electrically conductive materials arewell known in the art and can include, by way of non-limiting example,electrically conductive silicones, elastomers, polymers, epoxies, andresins, to name a few. In operation, the wireless sensor 102 is affixedto the patient's skin and the ECG electrode 702, exposed to thepatient's skin, senses and transmits electrical signals from thepatient's skin surface through the aperture 704 and the through-holevias 710 to arrive at an input to the ECG sensor 222.

FIG. 7E is a schematic bottom view of the embodiment of the disclosedwireless sensor of FIGS. 7A-D. The bottom surface of the bottom base 310is illustrated. Also illustrated in phantom (i.e., dotted lines) are theoutline of cut-out 362 which also indicates the position of the housing350 in relation to the bottom surface of the bottom base 310, and thelockable retractable reel 708. The ECG electrode 702 is also illustratedas it is positioned to make contact with the patient's skin. In someembodiments, the ECG electrode may be coated with a conducting gel toimprove the electrode-to-skin interface.

FIG. 7F is a schematic exploded perspective view of the embodiment ofthe disclosed wireless sensor of FIGS. 7A-7E. As shown, the ECG sensor222 is mounted on the top surface of the circuit board 340. The aperture704 extends through the mounting frame 330 and the bottom base 310 andis aligned vertically with the through-hole vias 710 (not shown in FIG.7F) and the ECG sensor 222. The aperture 704 and the through-hole vias710 are filled with electrically conductive material to form electrode702. Thus the disclosed structure provides electrical connectivitybetween the patient's skin and the ECG sensor 222.

FIG. 8A is a schematic exploded perspective view of an embodiment of thedisclosed wireless sensor having a temperature sensor 218, an acousticrespiration sensor 220, and an ECG sensor 222. FIG. 8B is a schematicbottom view of the disclosed wireless sensor of FIG. 8A. Structurally,the embodiment depicted in FIGS. 8A-B is a combination of theembodiments depicted in FIGS. 4A-C and 5A-C and 7A-F. As illustrated inFIGS. 8A-B, the temperature sensor 218 is mounted on the circuit board340. As previously described, inputs to the temperature sensor 218 arethermally coupled to multiple through-hole vias 410 located in thecircuit board 340. Under the through-hole vias 410 is an aperture 404which extends through the mounting frame 330 and through the bottom base310 of the wireless sensor 102. The aperture 404 provides access fromthe temperature sensor 218 to the patient's skin when the wirelesssensor 102 is worn by the patient. The aperture 404 and the through-holevias 410 are filled with thermally conductive material 402.

The acoustic respiration sensor 220 is mounted underneath the battery214, held in place by rim 221 that is sandwiched between the bottomsurface of the battery 214 and the bottom base 310. Accordingly, the rim221 serves to rigidly secure the acoustic respiration sensor 220 to thebottom surface of the battery 214. The acoustic respiration sensor 220protrudes through the aperture 502 in the bottom base 310, beyond theplane created by the bottom base 310. The acoustic respiration sensor220 transmits vibratory motion sensed from the patient (e.g., from thepatient's chest) through rigid structures of the wireless sensor 102such that the transmitted vibratory motion is sensed by theaccelerometer 210. The rigid structure through which the vibratorymotion is transmitted includes the battery 214 and the circuit board340.

The ECG electrode 702 is located within the bottom base 310 of thewireless sensor 102. An input to the ECG sensor 222 is electricallycoupled to multiple through-hole vias 710 located in the circuit board340. Under the through-hole vias 710 is an aperture or opening 704 whichextends through the mounting frame 330 and through the bottom base 310of the wireless sensor 102. The aperture 704 provides access from theECG sensor 222 to the patient's skin when the wireless sensor 102 isworn by the patient. The aperture 704 and the through-hole vias 710 arefilled with electrically conductive material to form the ECG electrode702.

In operation, the wireless sensor 102 is affixed to the patient's skin.The thermally conductive material 402, exposed to the patient's skin,transmits thermal energy from the patient's body through the aperture404 and the through-hole vias 410 to arrive at the inputs to thetemperature sensor 218. The acoustic respiratory sensor 220 sensesvibratory motion from the patient and mechanically transmits thevibratory motion to the accelerometer 210 mounted on the circuit board.And the ECG electrodes 702 and 707, exposed to the patient's skin, senseand transmit electrical signals from the patient's skin surface toarrive at inputs to the ECG sensor 222.

FIG. 8B is a schematic bottom view of the embodiment of the disclosedwireless sensor of FIG. 8A. The bottom surface of the bottom base 310 isillustrated. Also illustrated in phantom (i.e., dotted lines) are theoutline of cut-out 362 and the lockable retractable reel 708. Threesensor access points are shown in FIG. 8B. The thermally conductivematerial 402 provides a pathway for thermal energy to be transmittedfrom the patient's skin the temperature sensor 218 mounted on thecircuit board 340. The acoustic respiration sensor 220 is in directcontact with the patient's skin and in rigid structural contact with theaccelerometer 210 so as to mechanically transmit sensed vibratory motionemanating from the patient to the accelerometer 210 mounted on thecircuit board 340. And the ECG electrode 702 provides a pathway forelectrical signals to be transmitted from the patient's skin to the ECGsensor 220 mounted on the circuit board 340.

In some scenarios, it may be desirable to pair, or associate, thewireless sensor 102 with the bedside patient monitor 106 to avoidinterference from other wireless devices and/or to associatepatient-specific information (stored, for example, on the patientmonitor 106) with the sensor data that is being collected andtransmitted by the wireless sensor 102. Illustratively, suchpatient-specific information can include, by way of non-limitingexample, the patient's name, age, gender, weight, identification number(e.g., social security number, insurance number, hospital identificationnumber, or the like), admission date, length of stay, physician's nameand contact information, diagnoses, type of treatment, perfusion rate,hydration, nutrition, pressure ulcer formation risk assessments, patientturn protocol instructions, treatment plans, lab results, health scoreassessments, and the like. One skilled in the art will appreciate thatnumerous types of patient-specific information can be associated withthe described patient-worn sensor without departing from the scope ofthe present disclosure. Additionally, pairing the wireless sensor 102with the patient monitor 106 can be performed to provide data securityand to protect patient confidentiality. Some wireless systems requirethe care provider to program the wireless sensor 102 to communicate withthe correct patient monitor 106. Other wireless systems require aseparate token or encryption key and several steps to pair the wirelessdevice 102 with the correct bedside patient monitors 106. Some systemsrequire the token to be connected to the bedside patient monitor 106,then connected to the wireless device 102, and then reconnected to thebedside patient monitor 106. In certain scenarios, it may be desirableto share wireless communication information between a wireless sensor102 and a bedside patient monitor 106 without a separate token orencryption key. For security purposes, it may be desirable to usesecurity tokens to ensure that the correct bedside patient monitor 106receives the correct wirelessly transmitted data. Security tokensprevent the bedside patient monitor 106 from accessing the transmitteddata unless the wireless sensor 102 and bedside patient monitor 106share the same password. The password may be a word, passphrase, or anarray of randomly chosen bytes.

FIG. 9 illustrates an exemplary method of associating a wireless sensor102 with a patient monitor 106, which may be referred to as “pairing.”At block 902 the wireless sensor 102 is set to operate in a pairingmode. In an embodiment, a user initiates the pairing mode of operationfor the wireless sensor 102. This may include powering on the wirelesssensor 102, switching the wireless sensor 102 to a special paring state,and/or the like. For example, in certain embodiments, the wirelesssensor 102 may include a battery isolator 320 which, when removed,activates the wireless sensor 102. Upon activation, the default mode ofoperation is the pairing mode. In some embodiments, the wireless sensor102 may have a button/switch 324 that can be used to activate thewireless sensor 102 and place it in the pairing mode of operation. Forexample, a depressible button/switch 324 can be located on the topportion of the housing 350. When the button/switch 324 is depressed andcontinuously held down, the wireless sensor 102 enters into the pairingmode of operation and remains in the pairing mode of operation for aslong as the button/switch 324 is depressed.

As reflected at block 904, the wireless sensor 102 transmits a pairingsignal indicating that it is ready to pair, or associate, with a patientmonitor 106. According to some embodiments, the wireless transceiver 206of the wireless sensor 102 is configured to emit a low-power pairingsignal having a limited pairing signal transmission range. The limitedpairing signal transmission range helps to prevent unintended orincidental association of the wireless sensor 102 with a patient monitor106 that might be nearby but which is not intended to be paired with thewireless sensor 102. Such circumstances can occur in hospitals,healthcare facilities, nursing homes, and the like where patients,sensors 102 patient monitors 106 are located in close physical proximityto one another. In certain embodiments, the low-power pairing signal hasa pairing signal transmission range of up to approximately three inches.In other embodiments, the low-power pairing signal has a pairing signaltransmission range of up to approximately six inches. In otherembodiments, the low-power pairing signal has a pairing signaltransmission range of up to approximately one foot (i.e., twelveinches). A skilled artisan will recognize that other ranges can be usedfor the pairing signal transmission range.

Next, at block 906, the patient monitor 106, when within the pairingsignal transmission range, receives the pairing signal from the wirelesssensor 102. Upon detection of the pairing signal, the patient monitor106, at block 908, associates with the wireless sensor 102 therebyconfiguring the wireless sensor 102 and patient monitor 106 tocommunicate with each other. Once the pairing is completed, the patientmonitor 106 transmits a confirmation signal confirming that thepatient-worn sensor 102 is associated with the patient monitor 106,thereby indicating that the paring process has been successfullycompleted, as reflected in block 910. At block 912, the wireless sensor102 receives the confirmation signal. And at block 914, the wirelesssensor 102 exits the pairing mode of operation and enters into a patientparameter sensing mode of operation. In the patient parameter sensingmode of operation, the patient-worn sensor 102 transmits a patientparameter sensing signal having a patient parameter sensing signaltransmission range. The wireless sensor 102 increases the power of thepatient parameter sensing signal transmission range to a standardoperating range, such as for example, approximately three meters. Insome embodiments, the patient parameter sensing signal transmissionrange is approximately ten feet. In some embodiments, the patientparameter sensing signal transmission range is approximately thirtyfeet. In certain embodiments, the paring signal transmission range isbetween approximately three and twelve inches, while the patientparameter sensing signal transmission range is approximately ten feet.In such embodiments, there is at least an order of magnitude differencebetween the pairing signal transmission range and the patient parametersensing signal transmission range. Thus, the pairing signal transmissionrange is substantially less than the patient parameter sensingtransmission range. Once the wireless sensor 102 enters into the patientparameter sensing mode of operation, the wireless sensor 102 is then incondition to be placed on the patient to perform sensing and monitoringfunctions.

In certain embodiments, an extender/repeater 107 is used to communicatewith the wireless sensor 102 instead of than a patient monitor 106.Pairing with the booster/repeater may be performed in the same mannerdescribed above with respect to FIG. 9.

According to certain embodiments, the disclosed patient monitoringsystem 100 helps to manage a patient that is at risk of forming one ormore pressure ulcers by, among other things, detecting changes in thepatient's orientation and by determining how long the patient remains inthe present orientation. Advantageously, the system 100 can detect whenthe patient is repositioned and begin timing the duration that thepatient remains in that new orientation. Thus, if the patientrepositions on his own without the observation of a care provider, themonitoring system 100 can detect the repositioning event and restart atimer.

The patient monitoring system 100 can aid in the administration of aclinician-established turning protocol for the patient. For example, ifthe patient remains in an orientation beyond a predefined,clinician-prescribed duration, the system 100 can notify the patientand/or caretakers that the patient is due to be repositioned. Thewireless sensor 102 obtains sensor information indicative of thepatient's orientation (e.g., acceleration data), pre-processes thesensed data, and transmits it to a processing device capable ofprocessing the measurement data, such as, for example, the patientmonitor 106. Other devices capable of processing the measurement datainclude, without limitation, clinician devices 114, nurses' stationsystems 113, the multi-patient monitoring system 110, a dedicatedprocessing node, or the like. For ease of illustration, the descriptionherein will describe the processing device as the patient monitor 106;however, a skilled artisan will appreciate that a large number ofprocessing devices may be used to perform the described functionswithout departing from the scope of the present disclosure.

The patient monitor 106 stores and further processes the received datato determine the patient's orientation. According to some embodiments,the patient monitor 106 can determine whether the patient is standing,sitting, or lying in the prone, supine, left side, or right sidepositions. The patient monitor 106 can store the determined orientationinformation and keep track of how long the patient remains in eachdetermined orientation, thereby creating a continuous record of thepatient's positional history. In certain embodiments, the informationreceived from the wireless sensor 102 can be used to create atime-sequenced representation of the patient's positional history. Thisrepresentation can be displayed on the patient monitor 106 ortransmitted to a nurses' station or other processing node to enablecaregivers to monitor the patient's position in bed. The time-sequencedrepresentation can be viewed in real time and/or be accessed forplayback. For example, if an alarm alerts the caregiver that the patienthas exceeded the maximum amount of time to remain in the presentorientation, the caregiver can access and review the historical sequenceof the patient's orientations prior to and during that period of time todetermine the next orientation to which the patient may be repositioned.In some embodiments, the system 100 suggests the orientation to whichthe patient may be repositioned.

Illustratively, the patient monitor 106 counts the number of in-bedturns performed by the patient and displays the amount of time that haselapsed since the patient last turned. When the elapsed time exceeds aclinician-defined duration (e.g., two hours), the patient monitor 106displays an indication that the maximum time between patient turns hasbeen exceeded. The patient monitor 106 can also transmit a notificationto clinicians responsible for caring for the patient via, for example,the multi-patient monitoring system 110, a clinician notification device114, or the like. The patient monitor 106 can also determine and displaystatistical information, such as the average, minimum, and maximumamount of time between turns for a given clinician-defined time period,such as for example, twenty-four hours. The patient monitor 106 can alsodetermine and display the number of patient turns in the sameorientation over a clinician-defined period of time. Similarly, thepatient monitor 106 can display the total amount of time the patient hasremained in each specific orientation within a clinician-defined period.Moreover, the patient monitor 106 can determine the frequency andduration of periods that the patient remained in clinically-definedacceptable orientations.

In some embodiments of the present disclosure, the patient monitor 106accesses the patient's health records and clinician input via thenetwork 108. Illustratively, the patients' positional history data,analyzed in view of the patient's health records, may reveal or suggesta turning protocol (or other treatment protocol) that will likely yieldfavorable clinical outcomes for the particular patient. Accordingly, thepatient monitor 106 analyzes the accessed information in conjunctionwith the received information from the wireless sensor 102 to determinea recommended patient turn protocol (or other treatment protocol) forthe patient.

According to some embodiments of the present disclosure, the patientmonitor 106 assesses caregiver and facility compliance with theclinician-defined turning protocol established for the patient. Forexample, the patient monitor 106 can identify the number of times thatthe patient remains in a position for a period greater than theprescribed duration, as well as the length of each such overexposure.The patient monitor 106 can also track the time between issuance of anotification, alert, or alarm and action taken in response to the eventthat triggered the issuance, corresponding to clinician response time.

FIG. 10 illustrates a method 1000 of estimating and monitoring theorientation of a patient in bed according to an embodiment of thepresent disclosure. The method 1000 also identifies when the patientchanges orientation and keeps track of the amount of time the patientspends in in that orientation. The patient orientations that may bedetermined include, without limitation, whether the patient is prone,supine, on the left side, on the right side, sitting, and lying. In someembodiments, the patient monitor 106 determines the precise orientationof the patient's body. For example, the patient monitor 106 candetermine the degree to which the patient's body is inclined, verticallyand/or horizontally, thereby generating an accurate description of thepatient's orientation relative to the support structure (such as a bed)upon which the patient lies.

According to an embodiment of the present disclosure, measurements fromthe accelerometer 210 of the wireless sensor 102 are used to determinethe patient's orientation. The accelerometer 210 measures linearacceleration of the patient with respect to gravity. In some embodimentsthe accelerometer 210 measures linear acceleration in three axes. Oneaxis, referred to as “roll,” corresponds to the longitudinal axis of thepatient's body. Accordingly, the roll reference measurement is used todetermine whether the patient is in the prone position (i.e., facedown), the supine position (i.e., face up), or on a side. Anotherreference axis of the accelerometer 210 is referred to as “pitch.” Thepitch axis corresponds to the locations about the patient's hip. Thus,the pitch measurement is used to determine whether the patient issitting up or lying down. A third reference axis of the accelerometer210 is referred to as “yaw.” The yaw axis corresponds to the horizontalplane in which the patient is located. When in bed, the patient issupported by a surface structure that generally fixes the patient'sorientation with respect to the yaw axis. Thus, in certain embodimentsof the disclosed method 1000, the yaw measurement is not used todetermine the patient's orientation when in bed.

Illustratively, the described method 1000 continuously or periodically(e.g., every second) determines the patient's orientation based on themeasurements of pitch and roll provided by the accelerometer 210. Themeasurements are tracked over time, and the current measurement iscompared to one or more measurements in the recent past (e.g., theprevious few seconds) to determine whether an orientation change eventhas occurred.

The method 1000 is described in further detail herein with respect toFIG. 10. The method 1000 begins at block 1002 in which accelerationmeasurement data are received from the wireless sensor 102 by a devicecapable of processing the measurement data, such as, for example, thepatient monitor 106. Other devices capable of processing the measurementdata include, without limitation, clinician devices 114, nurses' stationsystems 113, the multi-patient monitoring system 110, a processing node,or the like. For ease of illustration, the description herein willdescribe the processing device as the patient monitor 106; however, askilled artisan will appreciate that a large number of devices may beused to perform the described method 1000 without departing from thescope of the present disclosure.

The acceleration measurement data may be provided directly from thewireless sensor 102 to the patient monitor 106, or the measurement datamay be relayed over a network such as network 108, by anextender/repeater 107, for example. The acceleration measurement datamay be initially sampled at a sampling rate suitable to provide anacceptable degree of precision, such as for example, 100 Hz. In someembodiments, the measured data are sub-sampled by the wireless sensor102 before being transmitted in order to reduce power consumption of thebattery 214 of the wireless sensor 102. In an embodiment, theacceleration measurement data are initially sampled at 100 Hz andsubsequently down-sampled, for transmission purposes, to a rate of 26Hz. In an embodiment, the acceleration measurement data are initiallysampled at a range between approximately 10 Hz and approximately 200 Hzand subsequently down-sampled, for transmission purposes, at a ratebetween approximately 5 Hz and approximately 40 Hz. A skilled artisanwill understand that many other sampling rates and sub-sampling ratesmay be used.

At block 1004, the patent monitor 106 determines the present orientationof the patient. The received acceleration measurement data are processedto determine orientation values for the roll and pitch axes. Theprocessed acceleration measurement data are provided in units ofdegrees, ranging from −180 degrees to +180 degrees. A lookup table,based on empirical data, provides a correlation between pairs of rolland pitch measurements and patient orientations. Illustratively, by wayof non-limiting example, a roll measurement of 180 degrees can mean thatthe patient is on his back, and a pitch measurement of 0 degrees canmean that the patient is lying down. Thus the combination of a rollmeasurement of 180 degrees and a pitch measurement of 0 degrees cancorrespond to an orientation in which the patient is lying down on hisback. Similarly, a combination of a roll measurement of 180 degrees anda pitch measurement of 90 degrees can correspond to an orientation inwhich the patient is lying on his right side.

FIG. 11A illustrates an exemplary plot 1100 of processed accelerometer210 data over time (from 0 to 450 seconds) used to determine a patient'sorientation according to an embodiment of the present disclosure.Initially, at for example, 50 seconds, the data corresponding to theroll (i.e., body length) axis 1102 is at approximately 180 degrees,indicating that the patient is on his back (i.e., in the supineorientation). The data corresponding to the pitch (i.e., hip rotation)axis 1104 is at approximately 0 degrees, indicating that the patient isreclining. Thus, combining the orientation information provided by theaccelerometer 210 with respect to the roll and pitch axes 1102 and 1104,the patient is determined to be lying on his back. At approximately 360seconds on the plot, denoted by vertical line 1106, we see that thepatient changes orientation. During a short transition period, the dataoscillates, as illustrated in the data representing the pitch axis attransition point 1108 and in the data representing the roll axis attransition point 1110. The oscillations can be caused by, among otherthings, jostling of the patient while moving from one position to thenext. Shortly thereafter, the data achieves a steady state, as reflectedby relatively stable graphs 112 and 114. Notably, the data indicative ofthe pitch axis 1102 has moved from approximately 180 degrees toapproximately 90 degrees. This corresponds to a ninety-degree rotationof the patient's longitudinal body axis to the patient's right side. Thedata indicative of the roll axis remains at approximately zero degrees,indicating that the patient remains in the reclining position. Thus,combining the orientation information provided by the accelerometer 210with respect to the roll and pitch axes 1112 and 1114, the patient isdetermined to be lying on his right side. In this manner, a lookup tableof patient orientation change actions can be created. The tableidentifies profiles (e.g., combinations of pitch and roll axismeasurements, within certain tolerances) of various possibleorientations that a patient can assume while in bed. The table ofprofiles of patient orientation change actions can be based on empiricaldata that is collected and analyzed.

Referring back to FIG. 10, at block 1006, previous patient orientationdeterminations are extracted and combined with the current orientationdeterminations to form a time window of patient orientation information.For example, the time window can include information indicative of thepatient's orientation from one or more time periods that are in closetemporal proximity to the present information indicative of thepatient's orientation, such as for example, the previous few seconds. Ofcourse, any number of previous patient orientations can be selected forthe time window. In an embodiment, the patient's orientationdeterminations for the previous two seconds are combined with thepresent determination to create a three-second time window of thepatient's orientation. The purpose for creating the time window is todetermine whether the patient has recently repositioned.

At block 1008, the time window is divided into segments for purposes ofanalysis. Any number of segments can be used for such analysis of thetime window data. In an embodiment, the time window is segmented intothree segments. In another embodiment, the time window is segmented intotwo segments. As illustrated in FIG. 11A at transition points 1108 and1110, it is possible that the measured data used for the time windowcontains multiple sources of noise, some of which can have spikes ofnotable magnitude. To reduce the impact of the noise in the analysis, asegment value for each segment is determined. As disclosed at block1010, the median value of the sampled data within each segment is usedto determine the segment values for each segment. By taking the medianvalue of each segment, a segment value is determined with minimal impactof potential noisy spikes. In certain embodiments, the segment value isa vector comprising values corresponding to each axis of measured data.Illustratively, by way of non-limiting example, each segment valuecomprises a vector including a roll axis segment component and a pitchaxis segment component. According to some embodiments, the units of thedetermined segment values and/or segment components are in units ofdegrees ranging from −180 degrees to +180 degrees.

At block 1012 the median values of each segment are pairwise compared.Illustratively, by way of non-limiting example, a time window that issegmented into three sections would have three pairwise comparisons: thefirst segment value compared to the second segment value, the firstsegment value compared to the third segment value, and the secondsegment value compared to the third segment value.

At block 1014, each pairwise comparison is analyzed to determine whetheran orientation change event occurred. The determination is made bycomparing the magnitude of the difference of each pairwise comparisonwith a predetermined threshold value. If the magnitude of the differenceof a pairwise comparison exceeds the threshold, then an orientationchange event is considered to have occurred. If the magnitude of thedifference of a pairwise comparison does not exceed the threshold, thenno change in orientation is considered to have occurred. Thus, a changethat exceeds a certain threshold in the roll dimension corresponds to anorientation change event that includes a rotation about the longitudinalaxis of the patient's body. Similarly, a change that exceeds a certainthreshold in the pitch dimension corresponds to an orientation changeevent that includes a transition from sitting up to lying down, or viceversa. A change that exceeds a certain threshold in both the roll andpitch dimensions corresponds to and orientation change event thatincludes a rotation about the longitudinal axis of the patient's bodyand a transition from sitting up to lying down, or vice versa. Accordingto an embodiment, the threshold is 45 degrees and thus, if the magnitudeof difference between any two segment values is greater than 45 degrees,then an orientation change event is determined to have occurred. Inanother embodiment, an additional comparison is made between consecutiveone-second segments of data to determine whether a change of at least 30degrees has occurred. This is to prevent repeated posture changes, whenfor instance, the patient is in a posture near 135 degrees, that is,right in the middle between two postures.

If an orientation change event is determined to have occurred, then atblock 1016, the detected event is classified. Reference is made to alook-up table of events which includes a set of profiles of orientationchange actions or activities. In an embodiment, each profile includesfour data points: a “before” and an “after” measurement for the rollaxis, and a “before” and an “after” measurement for the pitch axis. Forexample, as illustrated in FIG. 11A, the profile of the orientationevent activity of turning from lying on the back to lying on the rightside can be as follows:

TABLE 1 Roll Before Roll After Pitch Before Pitch After 180 degrees 90degrees 0 degrees 0 degrees

As illustrated in Table 1, the roll axis changes from 180 degrees to 90degrees indicating that the patient rotated from lying on his back tolying on his right side. The pitch axis does not change because thepatient remains in a reclining orientation. The table of events isdeveloped and updated off-line and is based on the analysis of empiricaldata of known orientation change events. Accordingly, classification oforientation change events can be performed by identifying in the look-uptable of events the orientation event profile that matches the data ofthe pairwise comparison when the magnitude of the difference of thepairwise comparison exceeds the predetermined threshold.

At block 1018, a vote is placed for the classified event.Illustratively, for the example described with respect to Table 1, thevote would be for the orientation change event profile of turning fromlying on the back to lying on the right side. At block 1020, the method1000 repeats the acts of determining whether an orientation change eventoccurred, classifying the orientation change event (if an eventoccurred), and voting for the classified orientation change event(again, if an event occurred), for each pairwise comparison. The maximumnumber of iterations for these blocks will be equal to the number ofsegments in the time window.

Once all of the pairwise comparisons have been analyzed, at block 1022,the method 1000 tallies the votes recorded at block 1018. Theorientation change event that has the most votes is determined to be theorientation change event that occurred. The determined orientationchange event is then reported as the orientation of the patient. Atblock 1024, an orientation duration timer is reset to keep track of thetime the patient remains in the new orientation. The method 1000 thenreturns to block 1002 to begin the analysis again with respect to thenext incremental (e.g., second) of measurement data.

If at block 1014, none of the pairwise comparisons result in a detectedorientation change event (i.e., the patient has remained in the sameorientation throughout the entire time window) then the method 1000progresses to block 1026 to determine whether the patient has remainedin the present orientation for a period of time greater than apredefined maximum duration, which may also be referred to herein as apredetermined duration or a predetermined maximum duration. If not, themethod 1000 returns to block 1002 to begin the analysis again withrespect to the next incremental set (e.g., second) of measurement data.If the patient has remained in the present orientation for a period oftime greater than the predefined maximum duration, then at block 1028,an alert is sent to, for example, the patient's caregiver, to notify thecaregiver that the patient should be repositioned. The method 1000 thenreturns to block 1002 to begin the analysis again with respect to thenext incremental (e.g., second) of measurement data.

FIG. 11B is an exemplary plot of an embodiment of a patient positionmonitoring paradigm for determining when a patient's orientation needsto be changed, according to an embodiment of the present disclosure. Inan embodiment, the plot 1102B may be part of a display to a caregiver ona bedside monitor, a multi-room monitor, both, or the like. The plot canbe updated in real time, at predefined intervals, and/or manually. Inother embodiments, the paradigm may be illustrative of the signalprocessing performed by a signal processor to determine when to activatean alarm informing a caregiver of the potential of a pressure ulcer if apatient is not repositioned. In these embodiments, each portion of theparadigm may be customized to a particular patient, patientdemographics, hospital protocol, unit protocol such as, for example, aprotocol specific to a surgical ICU or other hospital unit, home care,or the like.

In the illustrated embodiment, a patient's position is monitored overtime. A vertical axis 1105B represents time and a horizontal axis 1107Brepresents a patient movement event, such as, for example, In theillustrated embodiment, an alarm is set to alert a caregiver when apatient has been in a certain position for 3 hours or more. Theillustrated embodiment is a non-limiting example, as the alarm can beset to alert the caregiver at 1 hour, 2 hours, 3 hours, 4 hours, 5hours, 6 hours, 7 hours, 8 hours, 9 hours, and/or 10 or more hours. Thealarm can include a noise, color, and/or other indicator that will alertthe caregiver. In some embodiments, the alarm can indicate to thecaregiver that the patient has remained in the same position for athreshold amount of time (e.g., 3 hours). The threshold amount of timecan be predefined or adjusted over time. In some embodiments, the alarmindicates to the caregiver that the patient has fallen, moved into anincorrect position, left the bed and/or the like. In an embodiment,empirical data about a particular patient, or a group of like patients,can be used to customized some or all of the parameters for the alarmdiscussed herein.

As shown in FIG. 11B, the monitor begins monitoring a patient as thepatient is in Position 1 (e.g., the patient is lying on their back,side, front, sitting slightly up, sitting mostly up, or the like). Asthe patient remains in Position 1, a timing mechanism starts and a line1101B as its growth line. The slope of the line 1101B depicts a growthrate as the patient remains in the same position. As shown in theillustrated embodiment, the growth rate can be depicted linearly. Insome embodiments, the grown rate can be linear, non-linear, exponential,and/or the like. In some embodiments, the growth rate is predefined. Insome embodiments, the growth rate can change in real time and/or adjustto various physiological parameters and/or empirical data, as describedbelow. The growth rate can depend on a number of factors and empiricaldata already known and/or determined by the system, depending on forexample, how the patient's skin reacts to remaining in a singleposition, how fast negative effects experienced by the patient (e.g.,pressure sores) form or heal, the particular position the patient islying in, and/or demographic information about the patient, includingthe patient's age, health, blood perfusion rates, hydration, and/ornutrition, among others. Accordingly, in some embodiments, the growthrate can indicate a growth rate of the effects (e.g. bed sores) as thepatient remains in the same position (e.g., Position 1) over a period oftime.

As illustrated in FIG. 11B, the patient remains in Position 1 forapproximately 2 hours. At that time, the patient turns and/or is turnedby a caregiver to Position 2. In the illustrated embodiment, Position 2is a different position from Position 1. When the patient turns and/oris turned, the timing mechanism can restart a new line 1102B and beginto measure, track, monitor, and/or calculate the amount of time thepatient remains in Position 2.

A the same time, line 1101B transforms into its decay line. The decayline of line 1101B can comprise data relating to a decay rate of a bedsore, potential bed sore, particular area of a patient's skin, and/orthe amount of time the patient or a group of like patients, or allpatients, takes to recover from remaining in a particular position(e.g., Position 1), among other things. Similar to the growth rate, thedecay rate can be linear, non-linear, and/or exponential, among others.In some embodiments, the decay rate is predefined. In some embodiments,the decay rate can change in real time and/or adjust to variousphysiological parameters and/or empirical data, as described below. Thedecay rate may depend on a number of factors and empirical data,depending on for example, how the patient's skin reacts to remaining ina single position, how fast negative effects experienced by the patient(e.g., pressure sores) heal, how quickly the patient recovers, theparticular position the patient is lying in, and/or demographicinformation about the patient, including the patient's age, health,blood perfusion rates, hydration, and/or nutrition, among others. Asshown in the illustrated embodiment, when the patient is in one or morepositions that are not Position 1, the decay line of Position 1continues to decay at the decay rate. That is, in an embodiment, thedecay line of Position 1 will continue to decay at its decay ratethrough one or multiple other positions until it approaches zero so longas that other one or multiple positions do not include Position 1. Inthis example, the decay rate, or recovery rate for example, approacheszero more quickly the longer the patient remains not in Position 1.

In the illustrated embodiment, the patient turns and/or is turned againat Turn 2. Turn 2 occurs at a time before the threshold amount of timeis reached, and therefore, before the alarm alerts the caregiver to turnthe patient. At Turn 2, the patient turns/is turned to Position 3. Insome examples, Position 3 is the same as Position 1. In suchembodiments, because the decay line of line 1101B associated with theprevious Position 1 has reached zero, a line 1104B starts at zero as itsgrowth line for Position 3/1. However in some examples, Position 3 is adifferent position from Position 1. In the illustrated example, Position3 is different from Position 1 and its growth rate for line 1104B isdifferent from that of Position 1. In some examples, the decay line ofPosition 1 can continue to decay as the decay line of Position 2continues to decay when the patient turns and/or is turned to Position 3as long as Position 3 is different from Positions 1 and 2. In thisexample, the patient can continue to heal as a result of the effects ofremaining in both Positions 1 and 2. In some examples, Position 1continues to decay as the patient turned and/or is turned to multiplepositions, such as a second, third, fourth, and/or fifth or morepositions.

As shown in the illustrated embodiment, the patient remains in Position3 for a relatively short period of time. During that time, any effectsof remaining in Position 2 begin to decay. Thereafter, however thepatient turns and/or is turned back to Position 2. Advantageously,rather than restarting at time zero, the system can determine that thepatient has turned back to Position 2 and the timing mechanism beginstiming from the current value of the decay line of Line 1102B, whichcorresponds to point or time 1103B. Time 1103B is greater than zero inthis example, but less than the threshold amount of time. Additionally,in this example, the time 1103B is less than the amount of time thepatient originally remained in Position 2. In some embodiments time1103B can be equal to the time the patient turned from Position 2.However, in the illustrated embodiment, the system can take into accountthe decay rate and the time the patient has spent recovering fromremaining in Position 2. Thus, in the illustrated embodiment, Time 1103Bcan be determined by the system through a number of methods. Forexample, the system can subtract the recovery time from the growth time,and/or count down from the time of the turn (e.g., Turn 2), among othermethods. Advantageously, the preferred embodiment of the system canensure the patient does not exceed the threshold total time, taking intoaccount the growth and decay rate, a patient spends in a particularlocation. Although in an embodiment, the system restarts the timer ateach turn, without accounting for the previous time the patient spent ata particular position, such embodiments may not be as precise inallowing adequately recovery of tissue, blood pooling, or the likecaused by the previous position, and therefore, a patient may be morelikely to experience negative effects (e.g., bed sores). Accordingly,the preferred embodiment of the system can more precisely reduce alikelihood of a patient developing harmful effects, such as bed sores byensuring a patient would not remain in a particular position for toolong. Once the total time spent in a position, taking into account thepatient's growth and decay rates, reaches the threshold time (e.g. 3hours in this example), an alarm can alert the caregiver.

In some embodiments, the alarm will alert the caregiver until thepatient turns and/or is turned again, for example as illustrated by Turn4 in FIG. 11B. In some embodiments, the growth line will continue togrow, thus requiring longer for the line to decay, when a patient hasnot been turned within the threshold time. Such continued growth ensuresthat a patient will not be too soon returned to a position where thepatient spent too much time and can help ensure that the correspondingtissue has sufficient time to recover from a particular patientposition. In an embodiment, the decay rate of the line is adjusted toaccount for exceed the threshold limit. As shown in the illustratedembodiment, the decay rate is reduced after exceed a threshold, meaningit will take longer for the line corresponding to the alarmed positionto reach zero.

As discussed, in an embodiment, when the patient turns and/or is turnedafter the time of the alarm, the growth line will exceed the thresholdtime, as indicated by the plot of FIG. 11B. Once the patient turnsand/or is turned, the decay line can be shown above the threshold (e.g.alarm) line. In some examples, the patient may take longer to recoverwhen the time spent in a particular position exceeds the threshold time.In some examples, the alarm can alert the caregiver that the decay linehas reached the threshold time as the line continues to decay towardszero and the patient remains in a different position. In someembodiments, the alarm does not alert the caregiver that the decay linehas passed the threshold time.

According to certain embodiments of the present disclosure, the patientmonitor 106 determines the mobility status of the patient, e.g., whetherthe patient is ambulatory, standing, sitting, reclining, or falling. Thewireless monitoring system 100 can include an alert system to alert thecaregiver that the patient is falling, getting out of bed, or otherwisemoving in a prohibited manner or in a manner that requires caregiverattention. The alert can be an audible and/or visual alarm on themonitoring system or transmitted to a caregiver (e.g., nurses' stationsystem 113, clinician device 114, pager, cell phone, computer, orotherwise). Illustratively, the patient monitor 106 can display thepatient's mobility status and transmit a notification that the patientis active and away from the bed. In some circumstances, the patientmonitor 106 can determine whether the patient contravenes a clinician'sorder, such as, for example, instructions to remain in bed, or to walkto the bathroom only with the assistance of an attendant. In suchcircumstances, a notification, alert, or alarm can be transmitted to theappropriate caregivers.

In certain aspects, the information received from the wireless sensor102 can be used to create a time-sequenced representation of thepatient's movement. This representation can be displayed on the patientmonitor or transmitted to a nurses' station or other processing node toenable the caregiver to monitor the patient. The time-sequencedrepresentation can be viewed in real time and/or be recorded forplayback. For example, if an alarm alerts the caregiver that the patienthas fallen, the caregiver can access and review the historical sequenceof the patient's movements prior to and during that period of time.

In some embodiments, the patient monitoring system 100 can predict apatient's risk of falling based on analysis of the patient's movement(e.g., gait) and other information (such as, for example, the patient'scurrent medication regimen). When the patient monitor 106 determinesthat the patient's risk of falling is above a predetermined threshold,the patient monitor 106 can issue an alarm or alert to notify careproviders of the identified risk in an effort to anticipate andtherefore prevent a patient fall. Additionally, the patient monitor 106can determine when a patient has fallen and issue the appropriate alarmsand alerts to summon care provider assistance.

FIG. 12 illustrates a method 1200 of determining whether a patient hasfallen according to an embodiment of the present disclosure. The method1200 uses, among other things, information sensed by the accelerometer210 and by the gyroscope 212 of the wireless sensor 102 to determinewhether the patient has fallen. The method 1200 can be performed by thewireless sensor 102, using its processor 202 and storage device 204, orit can be performed by an external processing device that receives thesensed information from the wireless sensor 102, such as, for example,the patient monitor 106.

According to an embodiment of the present disclosure, measurements fromthe accelerometer 210 and the gyroscope 212 of the wireless sensor 102are used, among other things, to determine whether the patient hasfallen. As discussed above, the accelerometer 210 measures linearacceleration of the patient with respect to gravity in three axes. Thethree axes of the accelerometer 210 are represented in fixed, inertialreferences. The roll axis corresponds to the longitudinal axis of thepatient's body. Accordingly, the roll reference measurement is used todetermine whether the patient is in the prone position (i.e., facedown), the supine position (i.e., face up), or on a side. The pitch axiscorresponds to the locations about the patient's hip. Thus, the pitchmeasurement is used to determine whether the patient is upright or lyingdown. Advantageously, the pitch axis provided by the accelerometer 210can be a useful source of information in determining whether a patienthas fallen because it can indicate a change in the patient's orientationfrom standing to lying, a frequently-seen scenario when a patient falls.The yaw axis corresponds to the horizontal plane in which the patient islocated.

The gyroscope 212 provides outputs responsive to sensed angular velocityof the wireless sensor 102, as positioned on the patient, in threeorthogonal axes corresponding to measurements of pitch, yaw, and roll.In contrast to the fixed, inertial reference frame relative to gravityof the accelerometer 210, the frame of reference provided by thegyroscope is relative to the patient's body, which moves.

At block 1202, the method 1200 begins in which acceleration measurementdata and angular velocity data are received from the wireless sensor 102by a device capable of processing the measurement data, such as, forexample, the patient monitor 106. Other devices capable of processingthe measurement data include, without limitation, clinician devices 114,nurses' station systems 113, the multi-patient monitoring system 110, orthe like. For ease of illustration, the description herein will describethe processing device as the patient monitor 106. A skilled artisan willappreciate that a large number of devices may be used to perform thedescribed method 1200 without departing from the scope of the presentdisclosure.

At block 1204, the received data are normalized, which may also bereferred to as “scaling,” to adjust values measured on different scalesto a common scale, prior to further processing. According to anembodiment, training data are used to normalize the received data. Thetraining data can include empirical data of multiple fall scenarios aswell as non-fall scenarios that can be challenging to discriminate fromfall scenarios. The training data are collected and analyzed to serve asthe basis for establishing a weight vector (discussed below with respectto block 1208) used to determine whether a patient has fallen. Thetraining data can include multiple falling and non-falling scenarios,performed multiple times, by multiple subjects. Illustratively, by wayof non-limiting example, the training data can include the fall andnon-fall scenarios described in Table 2.

TABLE 2 Fall and Non-Fall Scenarios Fall forward from vertical, endingin left/right lateral position Fall forward from vertical, ending inprone position Fall backward, from vertical, ending in left/rightlateral position Fall backward from vertical, ending in supine positionFall to left/right from vertical, ending in left/right lateral positionFall to left/right from vertical, ending in prone position Fall toleft/right rom vertical falling, ending in supine position Collapse fromvertical, ending in left/right lateral position Collapse from vertical,ending in prone position Collapse from vertical, ending in supineposition Fall from vertical onto knees Fall from vertical to theleft/right against a wall, sliding down Take a step down repeatedly froma podium with left foot first Take a step down repeatedly from a podiumwith right foot first In bed: roll onto left/right side, falling out ofbed Sit down from vertical into a chair Jump off mattress repeatedlyStand quietly Stumble vigorously and fall onto mattress

As with the received data, each sample of the training data includes sixdimensions of information, corresponding to the three axes ofaccelerometer 210 data, and the three axes of gyroscope 212 data.Normalizing the received data standardizes the range of the variables ofthe received data. Since the range of values of raw data can varywidely, analytical algorithms may not work properly withoutnormalization. For example, many classifiers calculate the distancebetween two points. If one of the independent variables has a broadrange of values, the distance will be governed by this particularvariable. Therefore, the range of all variables can be normalized sothat each feature contributes approximately proportionately to the finaldistance. Normalization causes the values of each variable in the datato have zero-mean (when subtracting the mean in the numerator) andunit-variance. This can be performed by calculating standard scores. Thegeneral method of calculation is to determine the distribution mean andstandard deviation for each variable of the entire set of training data.Next each determined mean is subtracted from the corresponding variableof the received data. Then the new value of each variable (having themean already subtracted) is divided by the determined standarddeviation. The result is a normalized set of values that can be furtherprocessed by the method 1200.

At block 1206, the normalized set of values is processed to determinefeatures that are useful in determining whether a patient is falling.According to an embodiment, the method determines the following fivefeatures: the magnitude of the acceleration data (provided by theaccelerometer 210), the magnitude of the angular velocity data (providedby the gyroscope 212), the magnitude of the jerk (i.e., the rate ofchange of acceleration); the fall duration which is used to characterizea fall starting point and a fall impact point, and the change in pitchbetween two consecutively received data points. Other features canfeatures can be used in determining whether a patient is falling suchas, by way of non-limiting example, vertical velocities.

The magnitude of the received acceleration data is determined bycalculating the Euclidian norm of the three-dimensional vector made upof the measurements from the accelerometer's 210 three axes. As is wellunderstood by an artisan, this corresponds to the square root of the sumof the squares of the three accelerometer values, pitch, roll and yaw.Similarly, the magnitude of the angular velocity data is determined bycalculating the Euclidian norm of the three-dimensional vector made upof the measurements from the gyroscope's 212 three axes. The magnitudeof the jerk, which can also be referred to as “jolt,” “surge,” or“lurch,” is calculated by taking the derivative of the accelerationvector, and then calculating the Euclidean norm of the derivative.

The fall duration, which is a scalar value, is determined by evaluatingthe acceleration magnitude profile of the patient's motion over a shortduration of time. In particular, as the fall begins, acceleration of thepatient relative to gravity decreases because the patient is falling. (Apatient that is not falling would register an acceleration value in theup and down dimension equal to the force of gravity (i.e., 1 g orapproximately 9.80665 m/s²). Thus, if the magnitude of the accelerationis below a first threshold, then it is considered to be a starting pointof a fall, and the value of the fall duration is incremented by 1. Ifthe magnitude of the acceleration is above the first threshold, then thevalue of the fall duration is decremented by 1. In an embodiment, thefirst threshold is 0.6 g (or approximately 5.88399 m/s²). A secondthreshold is used to determine the impact point of the fall. In anembodiment, the second threshold is 0.8 g (or approximately 7.84532m/s²). If the magnitude of the acceleration is below the secondthreshold, then it is considered to be an impact point of the fall, andthe value of the fall duration is incremented by 1. If the magnitude ofthe acceleration is above the second threshold, then the value of thefall duration is decremented by 1.

The pitch change feature is the result of a comparison of the presentpitch orientation (as determined by the accelerometer 210 data) with thepitch orientation determined one second earlier. As discussed above, thepitch dimension of the accelerometer data is useful in detecting a fallbecause it distinguishes between the patient being in an uprightposition (e.g., standing up or sitting up) and reclining. Thus a changein pitch from being upright to reclining can indicate that a fall hasoccurred. The output of block 1206 is a five-dimensional feature vectormade up of the five determined features.

At block 1208, a weight vector of values is applied to the determinedfeatures. According to certain embodiments, the inner product of thereceived five-dimensional feature vector and a weight vector iscalculated. In certain embodiments, the weight vector is derived using amachine learning algorithm. Machine learning is a sub-field of computerscience based on the study of pattern recognition and computationallearning theory in artificial intelligence. It includes the developmentof algorithms that can learn from and make predictions on data.Algorithms developed through machine learning operate by building amodel from example inputs in order to make data-driven predictions ordecisions, rather than following strictly static program instructions.Machine learning is employed in a range of computing tasks where use ofexplicit computer programs is infeasible. When employed in industrialcontexts, machine learning methods may be referred to as predictiveanalytics or predictive modelling. As applied in the present disclosure,the machine learning system includes supervised learning, where themachine learning algorithm is presented with training data that includeexample inputs and their known outputs, given by a “teacher”, and thegoal is to learn a general rule that maps the inputs to the outputs. Inan embodiment, Fisher's linear discriminant is employed to derive theweight vector. Fisher's linear discriminant is a method used to find alinear combination of features that characterizes or separates two ormore classes of objects or events. The resulting combination may be usedas a linear classifier or for dimensionality reduction before laterclassification. Other methods of machine learning that can be used withthe present disclosure include, without limitation, linear discriminantanalysis, analysis of variance, regression analysis, logisticregression, and probit regression, to name a few. A skilled artisan willrecognize that many other machine learning algorithms can be used todetermine the weight vector without departing from the scope of thepresent disclosure.

The training data, described above, include empirical data collectedfrom multiple fall and non-fall scenarios which can be used to identifythe predictive indicators of patient falls. Illustratively, for eachtraining scenario, the five features described above with respect toblock 1206 are determined and provided as input to the machine learningsystem. Additionally, an output is provided for each training scenariothat identifies whether the scenario describes a falling event or anon-falling event. The machine learning system analyzes the trainingdata to derive a rule that maps the inputs to the outputs. According tocertain embodiments of the present disclosure, the output of the machinelearning system is five-dimensional weight vector that weights each ofthe five features according to their relative value in determiningwhether or not a fall has occurred. The weight vector is determinedoff-line and is provided as a fixed, five-dimensional vector to themethod 1200. Of course, the weight vector can be updated, based onanalysis of additional empirical data.

The inner product (also referred to as the “dot product” and the “scalarproduct”) of the received five-dimensional feature vector and the weightvector is calculated in a manner well understood by skilled artisans.The inner product yields a scaler value, also referred to herein as anactivation value, that may be either positive or negative. At block1210, the method 1200 determines whether a fall has been detected.According to some embodiments, the sign of the inner product of thereceived five-dimensional feature vector and the weight vector indicateswhether a fall has occurred. If the inner product is less than zero,then no fall has been detected, and the method returns to block 1202 tobegin analyzing the next set of data from the wireless sensor 102. Ifthe inner product is greater than zero, then a fall has been detectedand the method 1200 progresses to block 1214, where a notification,alarm, and/or alert indicating that the patient has fallen istransmitted to, for example, clinician devices 114, nurses' stationsystems 113, multi-patient monitoring system 110, and the like. Themethod returns to block 1202 to begin analyzing the next set of datafrom the wireless sensor 102.

In some embodiments, the system can determine a spatial location of thepatient within the patient's room. The system can monitor the room andspatially monitor and/or calculate how long the patient has been in aposition, when the patient was in the position, and/or how long thepatient was in the position, among other parameters. As discussed above,the system uses, among other things, information sensed by theaccelerometer 210 and by the gyroscope 212 of the wireless sensor 102 totrack the patient. This method can be performed by the wireless sensor102, using its processor 202 and storage device 204, or it can beperformed by an external processing device that receives the sensedinformation from the wireless sensor 102, such as, for example, thepatient monitor 106.

In some embodiments, the system can determine the position of thepatient within the patient's room, relative to certain features of thepatient's room, such as the patient's bed, a bathroom, a monitor, adoorway, and/or a window, among other room feature. In particular, usingmethods described herein, the system can determine a patient's verticalposition, vertical displacement, horizontal position, horizontaldisplacement, angular position and/or angular displacement in thepatient's room. For example, the accelerometer 210 and/or the gyroscope212 can monitor the patient's movements as the patient walks throughoutthe patient's room. The system can determine whether the patient isfalling, getting out of bed, or otherwise moving in a prohibited manneror in a manner that requires caregiver attention.

According to some embodiments, measurements from the accelerometer 210and the gyroscope 212 of the wireless sensor 102 are used, among otherthings, to determine whether the patient is bending down and/or hasfallen and/or where the patient has fallen (for example, by measuringthe vertical displacement of the patient and/or the height of thepatient relative to the floor). In some embodiments in which the patienthas fallen, the clinician can determine the location of the fallaccording to an embodiment of the present disclosure. As discussedabove, the accelerometer 210 measures linear acceleration of the patientwith respect to gravity in three axes. The three axes of theaccelerometer 210 are represented in fixed, inertial references. Thegyroscope 212 provides outputs responsive to sensed angular velocity ofthe wireless sensor 102, as positioned on the patient, in threeorthogonal axes corresponding to measurements of pitch, yaw, and roll.Based on these measurements, the system can determine whether thepatient has fallen according to methods described herein.

In such configurations, the system can record the position of thepatient. In certain aspects, the information received from the wirelesssensor 102 can be used to create a time-sequenced representation of thepatient's movement. This representation can be displayed on the display120 or transmitted to a nurses' station or other processing node toenable the caregiver to monitor the patient. The time-sequencedrepresentation can be viewed in real time and/or be recorded forplayback. For example, if an alarm alerts the caregiver that the patienthas fallen, the caregiver can access and review the historical sequenceof the patient's movements prior to and during that period of time.

FIGS. 15A-H illustrate various configurations of a room displaydisplayed on the patient display monitor. As illustrated in FIGS. 15A-H,the caregiver and/or patient can select any number of room items and/orconfigurations of the room items. The caregiver can select a room item,and place it within the room on the room display. The caregiver canrotate and/or place the room item in any configuration. In anembodiment, the caregiver could select the location of a major elementof a room at a time. For example, the caregiver could select a positionof the bed, then a position of the bathroom, then a position of thedoor, equipment, tables, chairs, couches, etc. In other embodiments,various room layout approximation are some to fully presented inselection screens and the determination of layout is made in one or justa few caregiver selections.

FIG. 16 illustrates an example method 1600 for detecting and/orpredicting a patient's fall, determining a particular location of apatient within a patient's room, and/or determining whether the patienthas moved outside of a prescribed movement of the patient, among others,for example.

At block 1602, the caregiver can enter a room configuration. Forexample, the caregiver can select any number of room items to bedisplayed in any number of configurations within a patient room display.The room items can include a patient's bed, a bathroom, a monitor, adoorway, and/or a window, among other room items. The caregiver canselect a room item by selecting, dragging, and/or dropping each roomitem around the room display. In some embodiments, the caregiver canselect a certain size for each room item. In some embodiments, thecaregiver can simply select a room item and select the location withinthe room display for the room item to be oriented and displayed. In someembodiments, the room item can be snapped into place in the roomdisplay.

At block 1604, the caregiver can optionally enter a movementprescription. For example, the caregiver can enter instructions to thepatient, including instructions to remain in bed, and/or to walk to thebathroom only with the assistance of an attendant.

At block 1608, one or more of the sensors described herein can beactivated. In some examples, the caregiver manually activates the one ormore sensors. In some examples, the system activates the one or moresensors automatically to begin tracking, monitoring, measuring, and/orcalculating certain physiological parameters, according to methodsdescribed herein.

At block 1610, the patient monitoring system 100 can predict and/ordetect a patient's fall and/or risk of falling based on analysis of thepatient's movement (e.g., gait) and other information (such as, forexample, the patient's current medication regimen). At block 1612, whenthe patient monitor 106 determines that the patient's risk of falling isabove a predetermined threshold, the patient monitor 106 can issue analarm or alert to notify care providers of the identified risk in aneffort to anticipate and therefore prevent a patient fall. Additionally,the patient monitor 106 can determine when a patient has fallen andissue the appropriate alarms and alerts to summon care providerassistance. The alert system can alert the caregiver that the patient isfalling, getting out of bed, or otherwise moving in a prohibited manneror in a manner that requires caregiver attention. The alert can be anaudible and/or visual alarm on the monitoring system or transmitted to acaregiver (e.g., nurses' station system 113, clinician device 114,pager, cell phone, computer, or otherwise).

If the patient monitoring system has not detected a patient's fall, thepatient monitoring system 100 can optionally determine whether thepatient has moved outside of the movement prescription. For example, asdescribed above, the patient monitor 106 can determine the mobilitystatus of the patient, e.g., whether the patient is ambulatory,standing, sitting, reclining, or falling.

If the patient monitoring system 100 determines that the patient hascontravened a caregiver's order, such as, for example, instructions toremain in bed, or to walk to the bathroom only with the assistance of anattendant, a notification, alert, or alarm can be transmitted to theappropriate caregivers at block 1612.

If the patient monitoring system 100 determines that the patient has notcontravened a caregiver's order, the system will return to block 1610 todetect and/or predict whether the patient has fallen.

FIGS. 13A-F illustrate embodiments of icon displays reflecting apatient's position according to an embodiment of the present disclosure.According to some embodiments, the graphical icons are used to visuallydepict the detected orientation of the patient. In particular, the iconsof FIGS. 13A-F show, in stick figure-type format, the patient sitting,standing, and lying in the supine position (on the back), the proneposition (on the belly), on the left side, and on the right side,respectively.

FIG. 14 illustrates an example of how the icons described with respectto FIGS. 13A-F can be presented on the display 120 of the patientmonitor 106. Toward the bottom of the main display 120 are a set of 3icons 1402, 1404, and 1406 indicating the patient's position. Theleft-most icon 1404 shows the patient lying on his right side. The twoicons to the right of the left-most icon 1404 and 1406 show the patientlying on his back. According to certain embodiments, the display 120 ofthe patient monitor 106 can include a touchscreen interface. Thetouchscreen interface can enable finger controls, including a touchgesture, a touch and move gesture, and a flick gesture. Illustratively,a clinician may use the touch gesture on an icon 1406 to expand the iconin the display 120 to include additional information associated withthat icon 1406. For example, additional information associated with the“touched” icon 1406 can include, the time at which the patient assumedthe particular orientation, the time (if available) at which the patientmoved from the orientation, the total duration of time the patient spentin the particular orientation, the number if discrete times that thepatient has been in the particular orientation over a defined period(such as 24 hours), the total duration of time that the patient thepatient has been in the particular orientation over a defined period(such as 24 hours), and the like. The clinician may also use the flickfinger gesture to scroll right and left, corresponding to moving forwardand backward in time, to access the historical positional record of thepatient.

The service life of the wireless sensor 102 disclosed herein can varydepending on, among other things, battery size, and data transmissioncharacteristics such as data rate, frequency of transmission, andquantity of data transmitted. According to one embodiment, the wirelesssensor 102 is configured to operate continuously or near continuously(e.g., waking up every second or so to sense and transmit the patient'sphysiological data) for approximately two days, after which the wirelesssensor 102 is to be disposed of properly. Other embodiments of thewireless sensor 102, equipped with a larger battery, for example, areconfigured to operate for longer periods of time before disposal. Someembodiments can be configured for sterilization and reuse.

Certain medical device manufacturers implement quality control measuresfor disposable medical devices, such as embodiments of the disclosedwireless sensor 102, to carefully control and manage the performancecharacteristics of their disposable devices. In particular, there is arisk that used and disposed-of wireless sensors 102 can be salvaged andrefurbished or retrofitted for additional use beyond the defined andintended service life of the wireless sensor 102. Features can beincluded in the disclosed patient monitoring system 100 to help preventimproper use of the wireless sensor 102 beyond its defined service life.

According to one embodiment of the patient monitoring system 100, thewireless sensor 102 is configured to set an activation flag in thestorage device 204 of the wireless sensor 102 upon initial activation,indicating that the wireless sensor 102 has been activated for use. Insome embodiments, the activation flag is set in an information element215 which is provided to store information about the usage of thewireless sensor 102 to help maintain quality control. Advantageously,the activation flag is set in nonvolatile memory of the storage device204, or in the information element 215, so that disconnection from thebattery 214 will not disrupt or erase the set activation flag. Thus, ifthe wireless sensor 102 is reconditioned such that it may be activated asecond time, the activation flag will indicate, through a standardsensor 102 start-up routine, that the sensor 102 has been previouslyactivated. Upon detection of the activation flag, the wireless sensor102 can transmit a prior activation message and/or alert which can serveas a warning notification that the quality of the sensor 102 may becompromised. The transmitted warning or alert can be received by, forexample, a patient monitor 106 which can then provide a menu of actionsthat the user may take in response to the transmitted quality warning oralert. The menu of actions can include the option to shut down thewireless sensor 102. In certain situations it may be desirable tocontinue to use the wireless sensor 102. Illustratively, it is possiblethat the battery 214 connection to the wireless sensor 102 isestablished and then unintentionally disconnected. For example, abattery isolator 322 may be initially removed from the sensor 102 butthen re-inserted so as to once again isolate the battery 214 from theelectronic circuitry of the wireless sensor 102. Removing the batteryisolator 322 a second time will result in transmission of a qualitywarning or alert as described above. In such a situation the user, beingaware of the circumstances that led to the quality warning, may chooseto continue to use the wireless sensor 102.

According to another embodiment, the wireless sensor 102 is configuredto set a prolonged service flag, after the wireless sensor has been inan activated state for a predefined period of time, such as, forexample, four hours. The prolonged service flag can serve to indicateupon start-up that the sensor 102 has previously been active for aprolonged duration of time. In another embodiment, the wireless sensor102 tracks and records on the storage device 204 the duration of timethat the sensor 102 has been active. Advantageously, the sensor 102 canissue notifications and/or alerts to the user that the sensor 102 isnearing the end of service life, providing the user an opportunity totake steps to replace the wireless sensor 102 before it ceases tooperate. Additionally, the recorded duration of time that the sensor 102has been active can serve to detect when a sensor 102 has beenrefurbished to operate beyond its intended service life. The appropriatewarning can then be transmitted to the user. According to someembodiments, once the wireless sensor has been active for a period oftime equal to a maximum service life duration, the sensor 102 sets aflag in the storage device 204, or otherwise configures itself toprohibit the sensor 102 from operating further.

In other embodiments, the wireless sensor 102 transmits to the patientmonitor 106 a unique identifier such as, for example, a product serialnumber that is encoded in one of the hardware components of the wirelesssensor 102. Once the wireless sensor 102 is paired with a patientmonitor or with an expander/repeater 107 and is operational, the patientmonitor 106 or the expander/repeater 107 can transmit the sensor's 102unique identifier to a central repository that lists the uniqueidentifiers of sensors 102 known to have been operational.Illustratively, during the pairing operation, the patient monitor 106 orthe expander/repeater 107 can check the central repository to determinewhether the wireless sensor 102 that is attempting to pair has beenlisted on in the central repository, thereby indicating that thewireless sensor 102 might have quality issues.

In other various embodiments, the wireless sensor 102 includes a sensorinformation element 215, which can be provided through an active circuitsuch as a transistor network, memory chip, EEPROM (electronicallyerasable programmable read-only memory), EPROM (erasable programmableread-only memory), or other identification device, such as multi-contactsingle wire memory devices or other devices, such as those commerciallyavailable from Dallas Semiconductor or the like. The sensor informationelement 215 may advantageously store some or all of a wide variety ofinformation, including, for example, sensor type designation, sensorconfiguration, patient information, sensor characteristics, softwaresuch as scripts or executable code, algorithm upgrade information,software or firmware version information, or many other types of data.In a preferred embodiment, the sensor information element 215 may alsostore useful life data indicating whether some or all of the sensorcomponents have expired.

Many other variations than those described herein will be apparent fromthis disclosure. For example, depending on the embodiment, certain acts,events, or functions of any of the algorithms described herein can beperformed in a different sequence, can be added, merged, or left outaltogether (e.g., not all described acts or events are necessary for thepractice of the algorithms). Moreover, in certain embodiments, acts orevents can be performed concurrently, e.g., through multi-threadedprocessing, interrupt processing, or multiple processors or processorcores or on other parallel architectures, rather than sequentially. Inaddition, different tasks or processes can be performed by differentmachines and/or computing systems that can function together.

The various illustrative logical blocks, modules, and algorithm stepsdescribed in connection with the embodiments disclosed herein can beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. The described functionality can be implemented invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the disclosure.

The various illustrative logical blocks and modules described inconnection with the embodiments disclosed herein can be implemented orperformed by a machine, such as a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general purpose processor can be a microprocessor,but in the alternative, the processor can be a controller,microcontroller, or state machine, combinations of the same, or thelike. A processor can include electrical circuitry configured to processcomputer-executable instructions. In another embodiment, a processorincludes an FPGA or other programmable device that performs logicoperations without processing computer-executable instructions. Aprocessor can also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. A computing environment caninclude any type of computer system, including, but not limited to, acomputer system based on a microprocessor, a mainframe computer, adigital signal processor, a portable computing device, a devicecontroller, or a computational engine within an appliance, to name afew.

The steps of a method, process, or algorithm described in connectionwith the embodiments disclosed herein can be embodied directly inhardware, in a software module stored in one or more memory devices andexecuted by one or more processors, or in a combination of the two. Asoftware module can reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of non-transitory computer-readable storagemedium, media, or physical computer storage known in the art. An examplestorage medium can be coupled to the processor such that the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium can be integral to the processor.The storage medium can be volatile or nonvolatile. The processor and thestorage medium can reside in an ASIC.

Conditional language used herein, such as, among others, “can,” “might,”“may,” “e.g.,” and the like, unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or states. Thus, suchconditional language is not generally intended to imply that features,elements and/or states are in any way required for one or moreembodiments or that one or more embodiments necessarily include logicfor deciding, with or without author input or prompting, whether thesefeatures, elements and/or states are included or are to be performed inany particular embodiment. The terms “comprising,” “including,”“having,” and the like are synonymous and are used inclusively, in anopen-ended fashion, and do not exclude additional elements, features,acts, operations, and so forth. Also, the term “or” is used in itsinclusive sense (and not in its exclusive sense) so that when used, forexample, to connect a list of elements, the term “or” means one, some,or all of the elements in the list. Further, the term “each,” as usedherein, in addition to having its ordinary meaning, can mean any subsetof a set of elements to which the term “each” is applied.

While the above detailed description has shown, described, and pointedout novel features as applied to various embodiments, it will beunderstood that various omissions, substitutions, and changes in theform and details of the systems, devices or methods illustrated can bemade without departing from the spirit of the disclosure. As will berecognized, certain embodiments described herein can be embodied withina form that does not provide all of the features and benefits set forthherein, as some features can be used or practiced separately fromothers.

The term “and/or” herein has its broadest, least limiting meaning whichis the disclosure includes A alone, B alone, both A and B together, or Aor B alternatively, but does not require both A and B or require one ofA or one of B. As used herein, the phrase “at least one of” A, B, “and”C should be construed to mean a logical A or B or C, using anon-exclusive logical or.

The apparatuses and methods described herein may be implemented by oneor more computer programs executed by one or more processors. Thecomputer programs include processor-executable instructions that arestored on a non-transitory tangible computer readable medium. Thecomputer programs may also include stored data. Non-limiting examples ofthe non-transitory tangible computer readable medium are nonvolatilememory, magnetic storage, and optical storage.

Although the foregoing disclosure has been described in terms of certainpreferred embodiments, other embodiments will be apparent to those ofordinary skill in the art from the disclosure herein. Additionally,other combinations, omissions, substitutions and modifications will beapparent to the skilled artisan in view of the disclosure herein.Accordingly, the present invention is not intended to be limited by thedescription of the preferred embodiments, but is to be defined byreference to claims.

What is claimed is:
 1. A method of detecting whether a monitored patienthas fallen by processing signals indicative of movement by the patient,the method comprising: receiving, with a processing device from awireless sensor, signals responsive to a linear acceleration of saidpatient with respect to a roll axis, a pitch axis, and a yaw axis, saidroll axis corresponding to a longitudinal axis extending along a lengthof said patient's body, said pitch axis corresponding to said patient'ships, and said yaw axis corresponding to a horizontal plane in whichsaid patient is located, wherein said wireless sensor is configured tobe worn by said patient and comprises an accelerometer, a gyroscope, anda first wireless transceiver, and wherein said processing devicecomprises a processor, a memory device, a storage device, a display, anda second wireless transceiver configured to communicate with the firstwireless transceiver; receiving, with said processing device from saidwireless sensor, signals responsive to an angular velocity of saidpatient with respect to said roll axis, said pitch axis, and said yawaxis; and processing said received signals responsive to said linearacceleration and said angular velocity of said patient with saidprocessor of said processing device, including electronically: forming asensor data vector comprising a plurality of data elements, each of theplurality of data elements responsive to one of said linear accelerationor said angular velocity with respect to one of said roll axis, saidpitch axis, and said yaw axis; normalizing said plurality of dataelements to form a normalized sensor data vector; generating a featurevector from said normalized sensor data vector, the feature vectorcomprising a plurality of features indicative of a patient fall, whereineach of the plurality of features are generated based on one or more ofthe data elements from said normalized sensor data vector; deriving anactivation value based on an application of weight vector to saidfeature vector, wherein said weight vector comprises a plurality ofweights, each of the plurality of weights corresponding to one of theplurality of features of said feature vector; determining whether apatient fall has occurred based on the derived activation value; andalerting a caregiver based on said determination, said alert indicatingthat said patient fall has occurred.
 2. The method of claim 1, whereinsaid normalizing said plurality of data elements comprises normalizingeach of said plurality of data elements to have zero-mean andunit-variance.
 3. The method of claim 1, wherein said plurality offeatures comprise: an acceleration magnitude; an angular velocitymagnitude; a jerk magnitude; a fall duration; a pitch change; andvertical velocities.
 4. The method of claim 1, wherein said applicationof said weight vector to said feature vector comprises computing aninner product of said feature vector with said weight vector.
 5. Themethod of claim 1, wherein said application of said weight vector tosaid feature vector comprises: presenting, to a supervised learningalgorithm, training data that include example inputs and known outputs;and mapping, by said supervised learning algorithm, said example inputsto said known outputs to derive said weight vector.
 6. The method ofclaim 5, wherein said mapping said example inputs to said known outputsto derive said weight vector is performed by Fishers' lineardiscriminant.
 7. The method of claim 1, wherein said determining whethera patient fall has occurred comprises identifying a sign attribute ofsaid derived activation value, wherein a positive sign attribute of saidderived activation value indicates that said patient fall has occurred.8. The method of claim 1, wherein one of said plurality of featurescomprises a fall duration, said fall duration determined by evaluatingan acceleration profile of said patient over a first time period.
 9. Themethod of claim 8, further comprising determining a starting point ofthe patient fall by comparing a first magnitude of acceleration duringthe acceleration profile to a first threshold.
 10. The method of claim9, wherein the first threshold is 0.6 g.
 11. The method of claim 9,further comprising determining an impact point of the patient fall bycomparing a second magnitude of acceleration during the accelerationprofile to a second threshold.
 12. The method of claim 11, wherein thesecond threshold is 0.8 g.
 13. The method of claim 1, wherein saidplurality of features comprises a pitch change, said pitch changedetermined by comparing a first pitch orientation of the patient with asecond pitch orientation of the patient, said first pitch orientationoccurring prior to said second pitch orientation.
 14. A method ofdetecting a patient fall, the method comprising: receiving, with aprocessing device, a first set of signals responsive to an accelerationof a patient from a wireless sensor, wherein said wireless sensor isconfigured to be worn by said patient and comprises a accelerometer, agyroscope, and a first wireless transceiver, and wherein said processingdevice comprises a processor, a memory device, a storage device, and asecond wireless transceiver configured to communicate with the firstwireless transceiver of the wireless sensor; receiving, with saidprocessing device, a second set of signals responsive to an angularvelocity of said patient from said wireless sensor; and generating asensor data vector comprising a plurality of data elements, each of theplurality of data elements responsive to one of the first set of signalsor one of the second set of signals; generating a feature vector fromsaid sensor data vector, the feature vector comprising a plurality offeatures indicative of a patient fall, wherein each of the plurality offeatures are generated based on one or more of the data elements fromsaid sensor data vector; deriving an activation value based on anapplication of a weight vector to said feature vector, wherein saidweight vector comprises a plurality of weights, each of the plurality ofweights corresponding to one of the plurality of features of saidfeature vector; determining whether the patient fall has occurred basedon the derived activation value; and alerting a caregiver based on saiddetermination.
 15. The method of claim 14, wherein the first set ofsignals is responsive to the acceleration of said patient with respectto a roll axis, a pitch axis, and a yaw axis, said roll axiscorresponding to a longitudinal axis extending along a length of saidpatient's body, said pitch axis corresponding to said patient's hips,and said yaw axis corresponding to a horizontal plane in which saidpatient is located.
 16. The method of claim 14, wherein said pluralityof features comprises a fall duration, said fall duration determined byevaluating an acceleration profile of said patient over a first timeperiod.
 17. The method of claim 16, further comprising determining astarting point of the patient fall by comparing a first magnitude ofacceleration during the acceleration profile to a first threshold. 18.The method of claim 17, further comprising determining an impact pointof the patient fall by comparing a second magnitude of accelerationduring the acceleration profile to a second threshold.
 19. The method ofclaim 14, wherein said plurality of features comprises a pitch changefeature, said pitch change feature determined by comparing a first pitchorientation of the patient with a second pitch orientation of thepatient, said first pitch orientation occurring prior to said secondpitch orientation.
 20. The method of claim 19, wherein said first pitchorientation is determined one second prior to said second pitchorientation.